It would be very understandable if her mom got trust issues and became unstable because her husband cheated on her. But how can she get in this situation when she's the one who cheated on him?
Crushing guilt over causing his death? Distorted and projected onto her daughter, but if you ignore logic you can see: "Gaudy boys will seduce you, making you abandon your True love."
Or something like that. Is what I imagine well see some chapters down the line.