The reason I enjoyed The Butterfly Effect so much is because it is "It's a Wonderful Death" several times over. Each time Evan gets a chance to try to fix his life, he messes it up more and more. Some things are better, others worse, and it cleverly ties together lots of plot lines. The last time Evan fixes things by going back to before he was born and kills himself in utero, and his mother, who has lost several pregnancies, utters the best line of the film: "Not again!" Unlike some other "It's a Wonderful Death" movies, Evan has no guide. He has lots of people that appear over and over in each of his lives, but none that is aware of what is happening and is there to help him. His father is aware, but tries to kill him. In the end, Evan makes the right choice to have never been born.

Note that the director's cut has this better ending. Apparently the original release had Evan simply rejecting Kayleigh's friendship so that she'd grow up with her mother instead of her father. The Director's cut is much more interesting, as they usually are.