Getting over someone is a grieving process. You mourn the loss of the relationship, and that's only expedited by 'Out of sight, out of mind.' But when you walk outside and see them on a billboard or on TV or on the cover of a magazine, it reopens the wound. It's a high-class problem, but it's real.
I've been divorced and I had to get back out there be single again and do some of that in the genuinely miserable state where you really do wonder what the hell is going on. And you feel like trying to have casual conversation with someone you don't know on the surface of the moon or something.
I did a lot of theater in college, and I knew that not many people make it, but I just figured, 'Well, I really want to try acting while I'm young, and I don't ever want to look back and say that I never gave it a try.' I fully figured I'd be back in grad school - probably for psychology.