I 24F think that my boyfriend 24M is into his brother’s girlfriend and I don’t know what to do

So this is the situation. My boyfriend and I have been together for a few years now. He lives with his older brother and his brother’s girlfriend.

I’ve always been a jealous person but it’s never been this bad, I tend to keep things in my head and never act out on those feelings of jealousy and insecurity. That being said, I think that my boyfriend is at the very least, interested in his brother’s girlfriend and I don’t know what to do.

It may be nothing but that’s ultimately the conclusion I’ve drawn. For the majority of our relationship, I’ve had no reason to worry about their relationship. We plan on moving in together at the end of the year though so I’m worried about it. Can this be nothing? Or is it so much more?

He’s known her for longer and has spent more time with her than with me. It’s natural being that they live together. We mainly only see each other over the weekend and very occasionally during the week. We both work and live 30 minutes away from each other so it can be tough working around our schedules but we manage it.

Now to the actual thing that’s bothering me.. my boyfriend loves physical affection. Despite this, he’s usually pretty distant with everyone outside his small circle and won’t touch them even playfully, but he’s very physical with me. He doesn’t do it as much with her but they’re very playful with each other. He’ll even offer her a hug when it’s obvious she needs one (his words). He’s not a hugger generally. I don’t get the feeling that’s she’s into him but It does feel like he may be into her. He’ll do things like playfully choke her or random things like that but it just feels like an excuse to touch her. She’s usually also into it. Which bothers me. It feels like he talks more about her than he does his brother. It always makes me feel like shit because that’s what you do when you’re interested in people. You find reasons and excuses to talk about them and interact with them.

I’ve never told him this and I honestly don’t want to in case it’s nothing and he then starts to think about that relationship in an unnecessary way. We’re moving in together and I’m worried. I realize that the obvious answer might be to just not be in a relationship right now but what should I do?

TL;DR: Boyfriend may or not be into his brother’s girlfriend. He’s physically affectionate with her and even playful. I don’t know how to navigate these feelings, we’re supposed to move in together soon.