She's not worried in the sense the rest of the world would be about a sexually straying spouse. No, she's worried Obastard will embarrass *her* again by acting giddy around a hot chick.
If she knew Obastard was screwing around secretly, she'd be OK with it, but these are public humiliations (like the selfie at the funeral).
I think she knows and somehow can deal with it as long as it’s someone “from the other team”.