I agree with the thread starter. A friend of mine went out with someone for over a year (at age 16 - talk about a waste of 6.67%+ of your life) and she's someone with... questionable promiscuity. Anyways, they're over, but he's not over it. The kid is so messed up now. He spent a few hundred dollars trying to ask her back out and she even said no. This was after she cheated on him with some kid who's an irresponsible drug user and someone else. I now consider him to be an idiot until he can get his mind clear. He knows he's stupid for still liking her; I definitely know it. It drives me crazy and, I'm sorry, but there's no reason to be going out with someone for that long if they're like that. No reason not to see what else is out there. No reason to take things so seriously. And I hate it when people become dependent on the other person. Drives me nuts, and doubly so when it's a close friend.
Had to say it. My advice: Date, but not for long enough that if you lost the person you'd be devastated. It's just a bad idea and a waste of time. I usually just think of people unable to get over things as mentally weak, and I stand by that as of this situation.