The Idea is Better Than the Reality
It’s a common warning when it comes to infatuation. You spend so much time thinking about the person that you fall in love with your idea of them, rather than the person themselves. Apparently, this guy didn’t think it through when he started this relationship and fell right into that trap.

Fifteen years is a long time to know someone, just to realize that you never really knew them at all. Maybe this guy had gotten so used to her saying no that he didn’t really want her to say yes. Some people like the thrill of the chase better than the real thing.
