I had a crush that started in high shcool and lasted for 2 years, but continued to have an impact for 4 years (so in total, 6 years). I met some other girls and such, but I couldn't do anything because I wasn't "emotionally available"... actually, this might have spoiled a big part of the social side of my studies.
I am very imaginative, and used to be sort of an idealist. I also have very high standards. So obviously, finding something that matches that point of view in the real world gets really hard.
Then one day I realized how much my imagination was a gift of a powerful tool as much as a curse of heavy chains, I realized how doomed I was to be able to have the ability to have such wonders in my skull that would never echo anywhere in the real world. That day, all these fantasies got broken and didn't work as they did anymore. I had discovered what others before me have called Weltschmertz (there's an article on wikipedia on that concept - basically it means "world-pain", it's the realization that the real world will never match your imagination and/or expectations).
I don't know if it's a good thing or not. I guess it made me a bit more cynic than I was, maybe a little bitter. But at least now I can see more clearly.