When Hawking was a graduate student at Cambridge, his relationship with Jane Wilde, a friend of his sister whom he had met shortly before his late 1963 diagnosis with motor neurone disease, continued to develop. The couple became engaged in October 1964 – Hawking later said that the engagement gave him "something to live for" – and the two were married on 14 July 1965.
During their first years of marriage, Jane lived in London during the week as she completed her degree, and they travelled to the United States several times for conferences and physics-related visits. The couple had difficulty finding housing that was within Hawking's walking distance to the Department of Applied Mathematics and Theoretical Physics (DAMTP). Jane began a PhD programme, and a son, Robert, was born in May 1967. A daughter, Lucy, was born in 1970. A third child, Timothy, was born in April 1979.
Hawking rarely discussed his illness and physical challenges, even – in a precedent set during their courtship – with Jane. His disabilities meant that the responsibilities of home and family rested firmly on his wife's increasingly overwhelmed shoulders, leaving him more time to think about physics. Upon his appointment in 1974 to a year-long position at the California Institute of Technology in Pasadena, California, Jane proposed that a graduate or post-doctoral student live with them and help with his care. Hawking accepted, and Bernard Carr travelled with them as the first of many students who fulfilled this role. The family spent a generally happy and stimulating year in Pasadena.
Hawking returned to Cambridge in 1975 to a new home and a new job, as reader. Don Page, with whom Hawking had begun a close friendship at Caltech, arrived to work as the live-in graduate student assistant. With Page's help and that of a secretary, Jane's responsibilities were reduced so she could return to her thesis and her new interest in singing.
By December 1977, Jane had met organist Jonathan Hellyer Jones when singing in a church choir. Hellyer Jones became close to the Hawking family, and by the mid-1980s, he and Jane had developed romantic feelings for each other. According to Jane, her husband was accepting of the situation, stating "he would not object so long as I continued to love him". Jane and Hellyer Jones determined not to break up the family, and their relationship remained platonic for a long period.
By the 1980s, Hawking's marriage had been strained for many years. Jane felt overwhelmed by the intrusion into their family life of the required nurses and assistants. The impact of his celebrity was challenging for colleagues and family members, while the prospect of living up to a worldwide fairytale image was daunting for the couple. Hawking's views of religion also contrasted with her strong Christian faith and resulted in tension. In the late 1980s, Hawking had grown close to one of his nurses, Elaine Mason, to the dismay of some colleagues, caregivers, and family members, who were disturbed by her strength of personality and protectiveness. Hawking told Jane that he was leaving her for Mason, and departed the family home in February 1990. After his divorce from Jane in 1995, Hawking married Mason in September, declaring, "It's wonderful – I have married the woman I love."