I met my boyfriend, at university, so I voted "school".
He was on the same nursing course as me. When I met him, I fancied him and so did my friend. However, my friend was already seeing a two other men. Two wasn't enough for her apprently, so she started dating my future boyfriend as well as two other guys! After one date with her, he started to be suspicious. So me and him started talking properly since we first met. He asked me if my friend was seeing other people. At this point they had gone to lunch together once, and were planning their 2nd date. I said that yes, she was - I had got tired of being used by her.
He ended it with that friend, and me and him continued to talk and eventually we started dating. My friend never forgave me for it. I know that he wanted to get back at my friend, and that might have been some of the motivation for getting with me, but I think that might have been part of my motive (she hurt me by going with him even though she knew I liked him, and she hurt him by cheating), as well as not having any genuine male attention for a long time. I know that at first I showed off about having him, and he did the same. That friend and her mates used to taunt me a lot about how my boyfriend was "using" me to get back at her.
Well, we've been together for just over a year now :p he's very romantic and spoils me with expensive presents. :D We never see that friend any more, and I've never felt so secure. At least its an interesting story to tell kids if we ever go that far. :p