Idk, I had a similar experience in my college classes. Male and female students - people were pretty cliquish and didn't seem interested in meeting anyone. I was rarely able to establish even light relationships via my classes, and these never progressed to deeper relationships.

And this doesn't seem like an "oh, that's just you" problem, since I had no problem meeting people at school events, in clubs, randomly on the quad, in the bars near campus, etc. Classes just, in general, seemed to put people in an asocial mood. Which honestly makes sense to me - if you spend an hour concentrating on a lecture and then have somewhere to be afterwards, you aren't very primed for the openmindedness and creativity necessary to interact with a stranger.