The truth is that nothing between Patty and Richard was ever going to last, because they couldn't help being disappointments to each other, because neither was as lovable to the other as Walter was to both of them. Every time Patty lay by herself after sex, she sank down into sadness and loneliness, because Richard was always going to be Richard, whereas with Walter, there had always been the possibility, however faint, and however slow in its realization, that their story would change and deepen.