The Big Sick exclusive: A look at the real-life love story behind one of this year's best comedies

And how the challenges and beauty of cross-cultural relationships have made the film such a beloved hit in the US

A real love story.

That's the simple, yet surprisingly rare underpinning that's helped propel The Big Sick into a surprise hit at the US box office, and cemented it as one of the best comedies of the year.

The film, written by those who lived it, centres on the relationship between comedian Kumail Nanjiani and writer Emily V. Gordon; Nanjiani plays himself, with Zoe Kazan filling in as Emily.

It's a multi-faceted story; Kumail and Emily are challenged first by certain cultural differences brought about by the former's traditional Pakistani Muslim upbringing, before a sudden mysterious illness strikes down the latter and leaves her in a terrifying coma.

A new featurette looks at the reality behind Kumail and Emily's relationship, mirrored so closely on screen, while a series of interviews examine the cultural challenges faced by three real-life couples.

Sadari (American) and Craig (British)

1) How did you meet?

Sadari: I was living in New York and Craig was travelling with a friend of his, they were doing a US tour and I met them in an Irish pub in the Murray Hill area of Manhattan.

Craig: I was three days into a year round the world trip, and we met in early January and were married in October. I'd been travelling for a lot of that year but I kept going back to New York and then Sadari flew out to Australia when I was there and stayed in Sydney with me for a few weeks. I was supposed to go onto Asia with my friend but I didn't and flew back to New York instead, and we were married a few months later, and then we told everyone afterwards! That was fifteen years ago.

2) Which aspects of your different cultures have helped in your relationships?

Sadari: We think if you connect then the different cultures don't really matter.

Craig: I've lived in London and Sadari's lived in New York. We're always lived our adult lives in very urban areas and we've got a lot more similarities and a lot more in common than if I'd met a British girl from the countryside.

3) What's been the funniest cross cultural moment in your relationship?

Craig: The race difference in Europe is a little more relaxed and America has a different history. The cultures there are very different; there is a bigger racial divide. Sadari's parents come from the age of the Black Power movement and grew up through that so its a lot more highlighted than it is over here.

So living in the US I had to adjust to that a bit. I remember early in our relationship we were in the car with Sadari's parents and she asked her Dad about an old friend and he said "haven't see them for a while, last I heard he'd gone and married a white woman". Sadari's mother immediately pipes up and says "Craig's in the car" and we laughed it off. I don't think you'd really experience it as much in modern Britain, but I had to adjust to it a bit in the US.

Sadari: Craig is really into the Northern Soul scene, but in the States we don't have that and don't see this type of scene, and I first saw it in the UK I was like "oh my god". Also once a very old potentially racist term was used towards me, the way it was used wasn't meant in a derogatory way but it did throw me off for a second.

4) Are there any cultural challenges / situations you've found in your relationship? How did you / your partner discuss them?

Sadari: We found a lot in America. Surprisingly a lot in New York. My parents live in Mississippi, and you would think we'd get more resistance there but in New York I was often yelled at by black men asking "why are you with this white devil". Every time Craig would take my hand black girls would suck their teeth. When we were in Mississippi when they saw Craig they saw he was white and then when they heard the cockney accent it threw them off a bit.

I think it had a lot to do with The Rolling Stones, they were into soul music and black people do know them. The British accent helps a lot down south, but in New York even to this day we still get looks, but we just ignore it.

Craig: There was an instance when Sadari first came to visit London with me, we were in a taxi out of Heathrow airport and a car pulled up alongside us. There were four young black guys in the car and they tapped on the window and Sadari looked over and said "oh here we go" expecting the similar grief we'd been getting in New York. These lads just pointed at me, put their thumbs up and drove off.

Sadari: That's when I was like "yeah I could stay in London!" I think living in London for the last twelve years, London is ten years ahead of the US. Race is not that big of a thing, where in the US its getting worse.

5) Describe the best thing about your relationship in a sentence

Sadari: Humorous and in-sync. If I pick up the phone to call Craig, he's about to pick up the phone to call me at the same time. We know when each other is thinking of the other. We tease each other and make fun of each other a lot.

Craig: We constantly mock each other on the American / British thing, which is interesting. The key thing is love is blind and borderless, we're very much proof of that.

Nadia (British) and Valerio (Italian)

1) How did you meet?

Valerio: I went to Birmingham to study at the university of Birmingham and the first or second weekend I went out with my housemate and I met Nadia at a club in Birmingham.

Nadia: He came to England on an Erasmus and I was just finishing my post grad course in Birmingham, and we went out clubbing and met. It's one of those things where I wanted to get into a club next door and I fell over as I was wearing high heels at the time. I said to the bouncer "please let me in" but he said "no you're too drunk" and I said "honestly I'm not I've just got ridiculous shoes on" so I ended up having to go to The Rainbow as it was the next club and we met in there.

Valerio: I think I added you on Facebook.

Nadia: I wasn't that interested to be honest!

Valerio: Then she replied to me and I was a bit surprised and we carried on from there.

Nadia: We're kind of stuck together now!

2) Which aspects of your different cultures have helped in your relationships?

Nadia: For me personally I think in the UK we tend to move very quickly, even things like eating, we don't sit down to enjoy food and simple pleasures. Being exposed to Italian culture, and not just tourist Italian culture but proper culture has made me slow down a little bit and enjoy what I'm doing and not be so materialistic.

I think Italians savour more experiences, they spend money on experiences rather than material goods. Even rich Italians have quite modest apartments, and for me it's understanding that family is really important. I tried to make my family the same and I'm so grateful that I have an Italian family as well to enjoy life and understand what's important.

Valerio: It's good as I see in the UK how things get done as I like being organised, which is very good for me.

Nadia: I think our personalities in general have a little bit of the other culture in it, for example he's got the British organisation and studies and works hard, and I've got like the "loud Italian woman who's over the top and a bit dramatic" personality.

Valerio: A match made in Heaven!

3) What's been the funniest cross cultural moment in your relationship?

Nadia: A massive thing for me was language. When we first met I was able to say what I wanted without his family understanding, which was very funny. There was a time where Valerio's granddad who is in his 90's was saying hi to me and he touched my boob by accident, and it was really funny. I was taking the mick in English and he was laughing with me and I was able to get away with it! But now they know a bit more English and know what I'm saying.

Valerio: When I first went to a British house it was a surprise to see a kettle; I'd never seen a kettle in my life. I was like "what do you do with this machine" and now I've learnt to make tea so now I'm a whiz and people keep asking me to make them a tea.

Nadia: I think it's little customs, when I first saw a coffee machine in Italy I was like "what is that, that's such an old fashioned machine" but its just how they make coffee and it's little things like that. Once we were stranded at the airport as Italians carry around paper I.D. rather than passports, so we've been stranded at airports being questioned, all sorts of things. There are so many bizarre things.

Valerio: The other thing I think about is Garibaldi biscuits. I don't think people know in Britain that Garibaldi is an actual person in Italy,

Nadia: Garibaldi is a biscuit to a British person. In Italy he's a hero, so when we went to a supermarket Valerio was like "why have you get our hero on a pack of biscuits"

Valerio: Language is hilarious.

Nadia: We made his Mum swear. She said it really loudly as she'd said it correctly and everyone turned round when she said f*** off.

4) Are there any cultural challenges / situations you've found in your relationship? How did you / your partner discuss them?

Nadia: Mainly language, which was challenging, but I've learnt Italian and we speak Italian all day every Sunday and we watch Italian programmes. Valerio's mum went to English classes, you just get around it. We forget there's more ways to communicate, like body language.

Me and Valerio's Mum agree on so many things and we're always ganging up on his Dad and she often knows exactly what I'm saying even though I'm speaking English as when I'm talking I move my hands. I never used to be so animated but s Valerio's family use their hands, I think it's a great way to communicate, using your body language rather than just words.

Another challenge is living away from family. Eventually we'd like to move to Italy, and we know that one of us is always going to be without our family, especially when we start a family of our own. One of us will always miss home but we're not even two hours away by flight and we talk on Skype all the time, with technology now it's not a huge deal.

My mum has said "you've got to stay in England for a good education" and Valerio's mum has said "well it's a better lifestyle here in Italy" so they are going to be arguing about where we bring up children. They'll get over it!

5) Describe the best thing about your relationship in a sentence

Nadia: We think we've managed to merge two cultures together that wouldn't of ordinarily have come together, and because of that we really think we're the richest people in the world. We've got access to so many different things, we can live in two different countries whenever we want to.

Valerio: When we are talking about Italian culture Nadia will ask a question that I wouldn't normally think of, so it's good for me to understand why she's asking these and I rediscovered by own culture thanks to her. It's really enriching.

Nadia: You get to know your own culture more. When you observe your own culture from another perspective you see a lot of flaws but you also see its beauty. I haven't felt proud to be British over the past few years, but when you see it from the perspective of someone else you think we have a lot of things as well as the flaws. It gives you a whole new perspective on life. It's worked for us for eight years.

Hanane (Moroccan/Algerian) and Roger (Italian/Greek)

1) How did you meet?

Roger: We met when Hanane was 17 as she was heading to work, I chatted her up! She took my number but we didn’t speak for several months, until one day Hanane called me. We then worked together for a couple of years until Hanane left for a life in Dubai until we met again after 8 years and I've never left her since.

2) Which aspects of your different cultures have helped in your relationships?

Roger: Both of our cultures have a strong belief in respect for others', whether it be faiths, beliefs, cultures, environment and more and we believe this helps in our relationship not to step on each other's toes! We let each other get on with what's 'normal' for us or our families and help when we can.

3) What's been the funniest cross cultural moment in your relationship?

Hanane: One of our wedding parties was in Morocco, and Roger dressed up in a Moroccan outfit as we were taken into the party venue. I was carried like a princess and Roger on a horse in a Moroccan outfit where the trousers are too short, because he wanted the legs of the trousers to be ankle length and insisted on it so when he sat up on the horse, you could see half of his legs - it did cause a giggle amongst the ladies!

4) Are there any cultural challenges / situations you've found in your relationship? How did you / your partner discuss them?

Hanane: Food. Food is always a problem down to the way the Sicilian people make certain foods and use a certain cheese, it has to be Sicilian or else it's an argument! “It's just cheese” I say to Roger, then I have to sit and listen to the importance of why Sicilian food is cooked a certain way and why they use this certain cheese. I understand and we move on, until the next time I attempt Sicilian!

5) Describe the best thing about your relationship in a sentence

Both: The love and respect we share. It has been a struggle to get to at times, but we are timeless!

The Big Sick hits UK cinemas 28 July.