There was a story I ran across a while back involving alternate chains of events. (Unfortunately, I don't remember all the details.) It went something like this:

There's a high-school boy who is being a typical self-centered teen boy about his girlfriend. Somehow that results in the girlfriend not being there to support her (female) friend, who then commits suicide. He then has the option of backing up in time and doing something differently, and the story plays out differently. I think it goes through more than one alternate option, too. In some of them, the friend doesn't die.

Does this sound familiar?