@boag Except for 3 things: 1) She got upset at her son for asking about his father to the point he ran away to the park. That could be explained away by a lot of things though. 2) MC was literally about to go confess to her and was talking about getting in her good graces through her son. He's too much of a weenie to try and get her to cheat, and he obviously knew about her husband. 3) Most importantly, her flashback showed a wedding ring. Current day does not.
I don't think she went mama bear because she's married. I think she went mama bear because she doesn't to risk another father figure disappearing in her life, hence the flashback starting with her swearing to never let it happen again after her own father died.