S04E01: It's a Wonderful Life

Eric is distraught after his break-up with Donna and wishes that they never kissed in the first place. As soon as he utters this wish, a guardian angel appears to teach Eric that it's better to have loved and lost than to have never loved at all. The angel takes Eric on a journey to the future -- the '80s -- to show him how everyone's lives would've turned out if he and Donna never got together. Eric remains unconvinced that the pain of his break-up was worth it, until the angel shows him all the wonderful memories he would have never had.