I think that once someone plays a game and it gets it's hooks into them, they will begin to form a scenario they want played out. That ultimate dream scene where their favorite character(s) are involved acting out the reader/player's strongest interest or fetish. It happens to me rather often, and I hope it happens to you, too.
Sadly, there are times it just doesn't happen. And if you're -really- invested in the story or some other aspect of the game, it can get to you. Sometimes I write up endings I wish happened in games I play, and it helps.
Sometimes...not so much.