Solo poly to primary partner

Hi all. I’ve been solo poly for about six years. I’m not exactly sure what I’m looking for maybe just support, maybe some gentle call-outs if I’m not seeing something clearly. I’m pretty sensitive right meow so please be kind.

This past year I started dating my current partner. Things have been really beautiful, and I’m deeply in love with him. I never thought I'd have a partnwr like him This is his first poly relationship, and it’s my first time practicing poly in this particular style. Early on, when he dated someone else, he withheld some information — not huge things, mostly his feelings. He downplayed them because he didn’t want to make me uncomfortable and because he felt guilty. That shook my trust, and I still feel the effects of that.

About six months ago, I started seeing someone casually. He’s been poly for six years, has a primary partner, and is very emotionally mature. I moved slowly mostly for my primarys sake, communicated clearly, and tried to be very supportive of my partner through it. It was hard for him. We had intense conversations sometimes twice a day for weeks. I stayed patient and understanding. My other partner was also very supportive. That connection eventually shifted into more of a comet dynamic.

Recently, I moved to be closer to my partner and to attend school. We essentially live together now. I haven’t built much of a community here yet, and I feel pretty alone outside of our relationship. I moved from a rich, socially active place to a more religious town that i dont love. My world feels small right now.

Two weeks ago, he met someone new. They’ve already seen each other seven times. She’s monogamous and single, which makes me uneasy. They’re also planning to travel out of the country together(a trip he had already committed to before meeting her) I’m really struggling with how fast this is moving. It feels like whiplash.

I don’t want him to stop seeing her. I don’t think I get to dictate what their time together looks like. But I feel scared, lonely, insecure, and resentful. Part of me feels hurt that he isn’t “doing the things I did for him” when I was dating someone else — even though I know I chose to show up that way. I’m realizing that being solo poly, I’ve never had someone so integrated into my daily life. I’m deeply attached to this version of our relationship, and now that it’s shifting, I’m afraid I won’t adapt well.

I’m worried that we set this partnership up in a way that doesn’t actually support polyamory long-term. I don’t know if what I’m feeling is reasonable insecurity, growing pains, or a sign of something misaligned.