He was away on business and then her co-worker hit on her and she knew she could get away with it. Her ex-boyfriend was in town and she still had feelings for him. Hubby got mono and a girl just gets horny after a couple of weeks without. The phrase contributing situation could mean just about anything, it doesn't mean he did anything wrong. And people don't always cheat out of dissatisfaction with their partner, they do it just because it felt good to have sex with someone other than their husband. And problems with a relationship do not result in sex with someone else. That's what your girlfriends are for.