I don't care. I'm not backing down on the punishment I gave my girlfriend's son.
Yeah, how does your girlfriend feel about it?
There's no need for her to know about my punishment
You should talk to your girlfriend about any problems you have with her son. Punishing him behind her back will lead to problems in your relationship.
I don't need to talk to her as I am her man and I can punish her son without her permission.
He's not your son so you don't really have a say in his punishment. Going behind her back is only going to cause conflict in the relationship and shows that you don't respect her as a parent. Is it really worth it?