[25M] I'm seeking help and guidance for dealing with PTSD within a relationship.

I have a feeling my boyfriend might be keeping something from me, but I'm not sure. We've been together for a while, and I’ve been dealing with PTSD, so it’s tough to discern whether my feelings are driven by fear or intuition. Lately, I've noticed something off about how he interacts with his phone. While I was away in the military, he got a privacy screen and mentioned that it was for work, which I respected. However, now that I'm back, he often keeps his phone turned face-down and holds it at a distance sometimes. He has a lot of gay friends, some of whom he’s hooked up with before we started dating, and while I understand that I can’t control his past, I can’t shake the feeling that something isn’t right. I’ve also observed that he rarely initiates sex or intimacy. The only times he seems more engaged are when he’s had a few drinks on the weekends. He tends to look around a lot, but I haven’t mentioned it to him. He follows hundreds of gay models and guys on social media, which makes me question things. I'm trying to work through my insecurities, but I wonder if my feelings are rooted in that. I’m currently in therapy to better understand myself and improve my relationship with trust. For those who have experienced PTSD, have you faced challenges in your relationships? I’d appreciate any advice you might have. I don’t have a wide circle of gay friends, which makes it seem like he knows someone wherever we go. I've encountered some difficult experiences within the gay community, which makes me prefer to stick to my own interests and comfort zone.