Spoilers for The Second Coming of Lucy Hatch

I found the "problem" to be entirely believable in this. Lucy is feeling very very guilty because her first marriage was not picture perfect. She wasn't in love with her spouse, and there was no passion. She wasn't overly upset when he died, and is overwhelmed by guilt by that. She is mourning what she didn't have more than she is mourning her dead husband. It was very well written.