I never went to university but I get the idea. I don't know if I ever 'pine' for days past enough to say that I long for them because I'm so caught up in my enjoyment of the present. I guess I could say that I wouldn't mind reliving the high school days when I would go to all the local punk shows but I can just as well have awesome experiences like that in the present, which I plan on doing.
So... yeah and no? Those days were fun just like the girls I've been involved with are worth looking back upon fondly but really, I've moved on. And it's not really a gradual thing, either, it's pretty much on/off. If I'm pining for someone, I give them my all. If it's unrequited, I can become depressed for a bit until I eventually do something to shake it off, and then I'm good as new, not even thinking about the person anymore.
I have no problem keeping in touch with girls from the past, though I haven't very much.