Advice

So I've been sleeping and having sex with someone for 3 years and I really feel like we should be together but I'm not really sure how he feels. My feelings have really grown for this person & i don't wanna just let it all go. I don't know how to ask him or how to tell him. We started off as fuck buddy's I hope that doesn't sound bad but it was what was going on. I think he feels the same way I do but I'm not sure