Chrissiejane, some of the stuff about the Tolkien marriage may just be speculation; it's hard to tell. Humphrey Carpenter is the Tolkien family's official biographer, and so I imagine Christopher had control over what appeared in the official biography and the letters that were published, also edited by Carpenter. (One of the letters in that volume, however, does include a long passage written to Christopher about the differences between men and women that is very interesting!) There is another biography, though, by Michael White. It's hard to tell how truthful this is: it is not written in an academic style and the author does not cite his sources. So take this for what it's worth.
White describes a marriage with some of the typical tensions that most marriages face. There were financial problems and Tolkien worked long hours trying to make ends meet and heading out to the garage at night to work on this long fairy book! He also continued to meet his male friends in the pub in the evenings. During WWII:
For Edith, this was a particularly unsettling and depressing time. Her sons were away facing danger and her husband was as involved with his male friends as he had always been. Edith had been forced to accept the fact that a large part of Ronald's life did not involve her. Indeed, in many ways, it excluded her. She did not like many of her husband's male friends and she avoided them. Whenever Jack [C. S. Lewis] visited the house in Northmoor Road, there was a frostiness between him and Edith . . .
She was still resentful of the fact that her husband had forced her into Catholicism and she attended church only rarely. Tolkien grew more pious as he grew older, but he did not try to further impose his beliefs on Edith. Her disinterest certainly frustrated him and their very different religious views remained an issue between them until the start of the Second World War when the couple had a major row and all the resentments and frustrations came out into the open.
Later on, however, during the 1960s, there were some changes. The Tolkiens were in retirement in Poole, where Edith had some friends:
She felt infinitely more at home here than in any other place in which they had lived, and the sort of people who stayed there (including many elderly residents) were Edith's kind of people, from similar backgrounds, similarly unpretentious and non-intellectual. Edith enjoyed playing cards with her friends, joining them for tea . . . The bungalow had a large garden which Tolkien enjoyed tending and the house was of a manageable size. For Edith, the few short years she had in Poole were probably the happiest of her life, but for Tolkien they must have often been torturous. He had no one of his intellectual calibre to talk to, he was gregarious and personable but the constant round of small talk over cream teas must have quickly grown irritating for him. Tolkein though appears to have seen this period as a necessary penance. He felt a deep and genuine love for his wife and in old age he may have grown to realise how unhappy she had been about certain aspects of their lives together.
Christopher tells us that the latest version of Aldarion and Erendis was made in 1965, so it's at least plausible that some of this history made its way into the story.