He clearly tells Ian that what he did was wrong, that you just don't fuck "your bro's girl" and that he should tell Wade. And he ends up saying, if you have a high relationship with him, "I've got your back, bro... Even if you're on the wrong side of the law.". IMO it's one of the few moments in the game where he acts as a true bro. Loyaly is telling your friends when you think they are in the wrong but backing them up anyway....He should've told Wade about it or should've made Ian end IanxCindy like the man he projects himself. Bullshit at it's peek. Fucker just an opportunist nothing more. How he behaves in-game is his character and he ain't no friend. He just tries to keep himself out of danger by not telling Wade.
Now I'm not saying that's the moraly right thing to do. I think that's were our disagreement comes from, you see it from a morality pov and I see it from a loyalty pov.