Total confusion and mixed signals from my partner (F28) (M27) I want to know whether I should cut my loses now or probe further?

So me (F28) and my partner (M27) have been in a relationship for 4 months now. He’s met my mum and sisters and I have yet to meet anyone on his side. Okay so his parents live abroad but he lives with his sister. I’ve never been introduced to her and I don’t even know if she knows I exist. He says he serious about me and wants us to move in together but some things are making me questions things for instance: on his birthday he bought his best friend to our dinner and said he had to do it otherwise people will ask why he’s spending his birthday alone .. erm hello? What about me? He says he doesn’t want people to “talk”. I’m in confusion