Books: Stephen Hawking: the man who mistook his wife for a nurse

Music to Move the Stars: A Life With Stephen by Jane Hawking Macmillan pounds

When Jane Wilde married a young research student named Stephen Hawking in 1965, she already knew he was seriously ill. A schoolfriend broke the news a couple of years before, saying that Stephen was suffering from "some terrible, paralysing, incurable disease". This is probably a fair representation of what was known then about motor neurone disease, long before the worldwide success of A Brief History of Time and Stephen's battle against the illness combined to raise its public profile.

What is striking about Jane's account of their courtship is her readiness to marry someone with such a grim diagnosis, whose physical condition was deteriorating before her eyes. Stephen's father bluntly told her that his son's life would be short, as would his "ability to fulfil a marital relationship", and advised her to have children quickly. His mother tried to warn her about the horrifying symptoms to expect, but Jane rejected the offer of information.

"I replied that I would prefer not to know the details of the prognosis," she writes, "because I loved Stephen so much that nothing could deter me from wanting to marry him: I would cook and wash and shop and make a home for him, dismissing all my own previous ambitions which were now insignificant by comparison with the challenge before me." It is hard to avoid the conclusion that Jane, who had not yet graduated from college, did not know what she was taking on. Although Stephen defied the imminent death sentence passed upon him, and is still alive today, the details of his physical decline are relentless.

Jane's determination to care for him, and to create an environment in which he could continue his ground-breaking work on black holes, takes up many more pages than her account of their eventual separation. This is not a vindictive book, although the agony she went through is palpable; if Stephen's struggle to keep his mind clear is heroic, so is her determination to balance his escalating needs and those of their three children. Jane emerges as decent and honest, even if her prose sometimes resembles the summaries of family news that fall out of cards at Christmas. But the book raises difficult issues, not in the way of Margaret Cook's spiteful demolition of her ex-husband Robin, but because it suggests connections of which its author seems to be unaware - and which she might find uncomfortable.

Hers is the story of a marriage based on a pairing of male ego and female submissiveness, the worldly manifestations of which she finds disturbing. In Cambridge, and at conferences all over the world, physicists gather in excited groups, while their wives are relegated to the status of second-class citizens. This is an early cause of dissent in the Hawking household, making Jane feel she has become "little more than a drudge, effectively reduced to that role which in Cambridge academic circles epitomised a woman's place".

In spite of this, she manages to bring up their children and even complete her own PhD. Cruelly, her husband's fame and his disease seem to progress in tandem, his body ever more wasted as his celebrity increases. Jane is gradually transformed from his wife into his nurse, her functions becoming "maternal rather than marital". That this development might be fatal to the marriage is obvious, although Jane hopes in vain for a new kind of relationship, based on intellectual companionship. Astonishingly for a woman with her conventional background and Christian beliefs, she responds by finding a friend and lover, a musician who is accepted into the household. This unusual arrangement is disrupted not by Jane's decision to leave Stephen for her lover, which she insists was never her intention, but her husband's eventual abandonment of her for one of his nurses.

At one level, this looks like a straightforward switch: a decision by a needy and imperious man to swap his wife-nurse, who has tried to save herself by developing limited interests of her own, for a nurse-wife who is willing to devote all her energies to him. The jarring note is not Jane's description of her distress at this turn of events, which is utterly convincing, but why it did not occur to her to leave a marriage in which she had come to feel so completely unvalued.

Her answer, that she still loved her husband, may be enough for some readers. What is suggestive, however, is her overwhelming need to believe in something - either God, whose existence is denied by Stephen, or that form of authority represented by her "genius" husband. Just before their marriage breaks down, she reveals to a journalist that her role no longer consists of promoting his success but of "telling him that he was not God".

In the context of their life together, it is easy to construe this as heresy, and to link it to Stephen's departure not long afterwards. It also goes some way to explain why, when Jane reflects on her life since the separation and divorce, she sounds a little directionless in spite of her own happy second marriage. Even if her marriage to Stephen Hawking developed into an uneasy alternation between maternal concern and filial rebellion, it seems to have provided her with a mission whose high cost she was never unwilling to pay.