That's not really uncommon. A lot of people I played with on CoD "Hated it" or "Definitely the worst entry yet." Yet every day... "<Gamertag> has started playing Modern Warfare 3." Sort of the nature of the beast.
I think calling it "Satan" is a little...overzealous, and probably doesn't help him at all. If they don't get along, he may be doing this to spite her to an extent...was he like this before she moved in to help with the baby? Even if it's a matter of spite or defiance, I think it's progressed well past that now.
I hate to be a downer...but I wouldn't anticipate the vanishing gamer act in a clan.

As an example, my clanmates and I met...5 years ago, I think? We don't play CoD anymore. We still talk often though. :/