This is why we need to take the attitude that we are "never off the market." The men and women I know look at marriage as "game over," and that they won.
The next question is, "now what?" Get fat? Stop having sex? It can cause a downward spiral. Once the chase is over - so to speak - then we become the jailers and the prisoners.
Life is a chase, a dance, and playful. Once we lose that playfulness and become serious, it truly moves the relationship to the end game and that's not good. .