Im about to share what happened last night, but I guess my question really revolves around when to be confrontational and when to be indifferent.

So Me, my new ltr, and some friends were drinking and hanging out. Also, there was one dude there who is the son of my fathers new girlfriend, so this was like our 3rd time ever hanging out. An important note is this guy fucks, he's a player and knows women.

So we were all a bit drunk and the son of my dads gf was very drunk, but still no excuse for what he did. While I was in the bathroom, he gets close to my ltr and tells her she's pretty, (she told me so green flag in my book), she obviously rejects and just says "thanks" then got up to find me.

She told me about 30-40 min after this happened when it was just me and her. Since this was a potential brother in law, and knowing how he is with girls, I decided to go set a boundary. It was just me and him and I told him very sternly, "If my dad and your mom are going to be dating, don't you fucking dare disrespect me and make a move on any girl im with, or you'll face the consequences." He plays dumb and acts like he has no idea what im talking about, but I think he knew.

Anyways, did I do the right thing in this situation?

How do you guys know when to be direct with someone and mate guard, or be indifferent ?