Thing is, yes, the mom was a bit of a bitch for pulling that stunt, but the dad also made his choice. They both agreed that MC's babby daddy is off-limits, but she still went and had lunch with him. She broke that promise, and the dad divorced her. She played him. It happens. Letting the player choose whether to forgive their mother or distance themselves from her was a brilliant opportunity for players to express themselves in an ethically grey situation.
With the overcorrection, all Nyx did was cover up shameless behaviour that should be shameful. The mother should be regretful, the dad has the right to be angry and leave her. What she's done is essentially excuse mom's behaviour which sends the wrong message to men and women.