Is it ok to ask the partner for threesome

We’ve been together for five years now (27 & 29). We have sex regularly, around 2–3 times a month. Our sex life is pretty good, but sometimes I’m not sure if we’re both fully satisfied with it.

My partner is a vers top. I rarely top him because I’m more of a bottom, but sometimes I get the feeling that he also wants to bottom and I’m not able to fulfill him in that way as much.

On my side, I didn’t have much sexual experience before we got together. So even at 27, I still feel curious, especially about trying a threesome. He once told me he had one before( and other hot guys’ dick, have to admit that his dick is not much exciting to me anymore). We’ve never really talked about it seriously, but I’ve been wondering if trying something like that could bring something new to our sex life and make it more exciting for both of us.

I’ve also thought a bit about open relationships, but honestly, I don’t think I’m ready for that. I still want our sexual experiences to involve both of us. And to be honest, I’d feel insecure thinking about him having sex with someone else without me.

Is it okay to feel this way? How should I bring this up to him?