When they're younger they get over it quickly because they have lots of options. They don't really worry about finding someone else really great because the sexual marketplace favors attractive, thin, socially presentable women in their 20's. It's nothing to really worry about. In fact, you'll probably have the last laugh once you get your money right and your education game on point while they wither away like dried up pieces of fruit.
Then they look back. They look back at all the amazing, motivated, good looking, ambition-in-his-eyes type of guys that they turned down in their 20's. They look at themselves and see a body that's beginning to sag. They're starting to see streaks of gray where they had told themselves before that the stray grays were coming from stress. They remember the look of hurt in the man's eyes that they turned down, they cracking of his voice as he asked why she didn't love him, the bitter spiral he may have gone down once it was over... and now she looks at the options that she has currently.
The limited options that she has now: guys that are willing to take a woman who is very much past her prime, has a kid at this point probably, and is showing distinct signs of aging. She'll say that she's "had her fun" now, but in reality she knows that her options are quickly dwindling and that she has to cash out as quickly as possible before she's doomed to never having kids, ever. She'll more than likely find herself forcing the word "yes" out through clenched teeth to a man's marriage proposal who is inferior to the five guys that she turned down in her 20's.
And then there's you. What kind of man are you? Do you want to be the guy who was completely sunk and ruined by a pretty girl that got to your head? Or do you want your life to be centered around you? I know that we're young and dumb and the first time that we fall in love we fall hard, but it's not as if it's something that we can't recover from. I've made stupid decisions over a woman before, but it's not the end of the world if it ends. You just gotta keep on "keepin' on."
Does a part of me still love the woman who did me really dirty? Yeah, I can admit that. But I don't let it consume me in a negative way. I use it to remind myself of where I went wrong, where not to let people wrong me, and to remind myself that love is real and that if I maintain an open heart and mind, it can happen again.