Conflicted about what to do

I (m27) am currently in a monogamous relationship with my partner (m25) for 6 years. I’ve had these feelings in the back of my mind for a while but they’ve suddenly surfaced more recently. I feel as if I don’t get the sexual or affectionate satisfaction from him anymore. We never have sex, and he doesn’t kiss me , etc

I recently suggested having an open relationship but he was definitely not for it and we argued about it but I’ve talked to him about my needs and how I feel and I feel like nothing is changing. I also feel like I’m not meant to be monogamous at this point like I’d be unable to do it right without cheating.

Part of me wants to just say that I can’t be with him if we aren’t in an open relationship and then just do my own thing from there but I’m also scared of losing the life we’ve made together these past few years. I’m terrified to say anything like that to him.

Considering starting therapy to talk about these issues as well.

Any advice would be welcomed or if people have had similar experiences?