I’m not sure what to think

I feel like my boyfriend has a thing for his sister. I feel like there has been several occasions where weird remarks were made. So when I lived with them before we got our own place me and his sister were close. We wore each other clothes and I bought her clothes as well she was like the sister I never had anyways I was wearing her shorts and my boyfriend had said “you look better in those shorts then my sister.” Immediately I thought wtf??? I talked to him about it and I told him it was really weird how he said that and it made me uncomfortable that 1 that TO ME the way I perceived it was he finds his sister attractive and looks at her in those shorts inappropriately and 2 he’s comparing me with his sister in that way.

It was weird. Then another situation is where his sister actually asked me about her brothers size and specifically asked me if it was big….like wthell? It was only grossing me out so now recently his sister sent him a picture and I guess he didn’t want me to see because when I was on his phone (with him beside me he was letting me be on his phone) I guess there’s a new update for the iPhone that shows deleted messages and when he saw that he immediately took his phone and wouldn’t let me see it and it was just really odd he started getting really mean and wouldn’t let me see even when I told him I wouldn’t be mad. He then told me his sister was showing him her tattoos . Days later he showed me the picture and it was a picture of her taking a selfie in a bra and I was telling him you couldn’t even see her tattoos clearly or anything. I can’t help but have this gut feeling something is off about them does this sound normal?