"Don't leave a lukewarm, sort-of-compatible relationship for one that seems to burn hotter, better, with someone even more compatible than you thought possible in your current/old one" isn't exactly a common-knowledge approach to handling relationships. In fact, it even conflicts with a lot of the advice readily offered on this board.

She wasn't getting with the new guy because she was afraid of being alone - She was hooking up with him because she felt 'more romantically compatible' with him than than she did with her husband, until she learned otherwise.

I'm tempted to bring up Pina Coladas and getting caught in the rain to explain it.