Betsy hadn't had sex, actual; sex-sex, full sex, in two hundred and fifty-three days. She decided on her thirty-seventh birthday that she wouldn't sleep with anyone unless it was in the context of a committed relationship which had some sort of future, and she was only gradually coming to the realization of what happens when a woman her age makes a decision like that: she never has sex again.
She knew that what she was going through was nothing special, just garden-variety heartbreak, the sort of thing that poets and novelists had been writing about for hundreds of years, but she also knew, from those same books, that there were people who never recover form it, ones who go on through life beset by a dim and painful longing.
Why does anyone stay in an unhappy relationship? Because people do. They do it all the time. And the truth is, when you’re in it, when you’re up to your neck in the everyday part of life with another human being, sometimes you don’t exactly notice how bad things really are. It’s not always as apparent as it would seem. Unhappiness, when it involves another person, can be like that line from The Sun Also Rises about going bankrupt, how it happens two ways: gradually, and then suddenly.