Yet again, I'm here! Airing my dirty laundry...

Despite all the red flags, I'm still just strolling along unhappily/happy in my "bullshit ass relationship" as I call it with my SO. We've been doing good..no arguing but you know why?! Bc j accept the fact he's going to do whatever the hell he wants and I will not be a priority. We haven't had sex in hmmm over 4 weeks, only spend time together maybe once a week..yea, it pretty much sucks. But today I'm here with another little altercation from him. Well see fb will tell you all the pictures a person has "liked". I noticed that he became friends with a woman that just gave me a bad gut feeling. Well I've been doing good at not looking but tonight I got curious. I see he has been liking a lot of her pictures in the past few weeks. Soooo..I ask him how he knows her, he said i don't know who that is but why do you ask? I said oh I'm jw, he said no you don't ask for no reason..how do you know her? I said I didn't say I did. Well he hangs up with me very quickly..I call him back an hour later and ask was he not going to say good night, he said, well the way you were tripping, I didn't know if I should...oh ok?!? So I say I was jw how you know the girl. He said, I don't really..but he ask me prob 3 times how I knew her and why I wanted to know. It's odd to me. Seriously why was it such a big deal how I knew her? Why couldn't he answer. Am I being irrational?! It shouldn't be this hard to trust someone..what do I do from here?