Are we really just friends?

I have a friend group of 9 girls and in this group of friends I’m in a trio and we’re very open about it and the rest of our group knows this. One of my friends from our trio has an older brother that I am kinda of friends with. We talk sometimes when I’m with this friend but that’s it. A few days ago, when we all gathered for a group party, she told me that she thinks that her brother likes someone from our big group of friends. I was curious and wanted to know who she thought it was but she wouldn’t tell me. I was saying names from our group trying to guess who it was. She said that it was only a guess and that she promised herself she wouldn’t say who it was. When she said this I had a thought, “is it me?”. I honestly felt ashamed and almost guilty for thinking of it because she was one of my best friends, so I pushed the idea away. I later texted her and guessed and few other girls from our group but she said that she was wrong about him liking anyone from our group and said he doesn’t like anyone. But, I started seeing him more than before and noticed things he did that I didn’t see before. I noticed that when he would talk to his sister (my friend) when I was by her, I seemed different then when he talked to other people, it’s hard to explain but he wasn’t his stern (?) and less loosened. It’s hard to explain but there was a difference before we came up to him and when we did. I also remember his friend look towards us and then my friends brother turning around immediately, kinda like when someone touches you on the shoulder and you flinch (?). My mom also one day randomly had asked if he (my friends brother) likes anyone and I told her about what my friend said and she told me that my friend probably did that because it is me and is trying to cover it up. I don’t know if he does like me, but i hate that I keep thinking about it because she is my best friends brother and it just feels wrong, anyone have an idea of what’s going on?

Are we really just friends?
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