Here's the situation:
You meet a girl/guy one night, you both really hit it off, and one thing leads to another and you both end up getting horizontal. It's all good, and both parties have fun, but you realize that it was a one time deal, and that's cool. Well, a little time goes by...and WAM! You see the person again. You talk, and somehow you get on the subject of that night (or hours, or hour) spent of passion. You both acknowledge that, "Hey, it was fun, and I've thought about you since then", and you both decide that maybe Round 2 is in order.
So there the two of you are, anticipating that lightning will strike again...you go to do the deed...and the fireworks aren't there! You both know it, but neither of you wants to say anything, so it is a VERY uncomfortable situation. Not that it's BAD, but just like most sequels, it's not as good as the original.
Then you start to wonder...Why? Was I just drunk/horny/lonely/needy the first time? Then what happens if you see the person again on campus, or at another party? Do you avoid them? Knowing that there will never be a Round 3, do you laugh it off? What to do???