Considering breaking up (Please Help!)

I'm considering breaking up with my boyfriend of 8 months.

I'm dating my sister's husband's cousin who lives with them, so I'll start from the beginning🙈 We never got to the part where we made it official. We hooked up at my sister's wedding planning party (one of many) and we just became a thing after that. There was no talk about how we were a couple or anything, we just kind of subconsiously decided that we would be a thing. I didn't expect anything serious to come from it but within the first month he told me he loved me. A week after that I told him I loved him too, mainly because I felt like I needed to say it, but also because I thought I would grow into loving him.

Fast forward to now and I do love him, but I'm not IN love with him. He's not very good at communicating (I've told him that but he says that's just how he is) and I've constantly had to pester him about what's bothering him if he's down because he doesn't tell me personally. It's gotten to the point where I just don't bother anymore and let him ride the waves out himself, because even if I ask him what's wrong, he'll say he doesn't know and I can't help in any way. We don't say goodnight to each other anymore and we don't make plans to see each other. If it wasn't for family gatherings then I probably wouldn't have seen him at all in the last two months.

I've been thinking about breaking up with him for weeks now but today was the first time that I actually seriously considered it and started thinking about how to do it. Can anybody give me any advice as to how to do it so that things stay amicable?? He is still family after all and I'll have to keep seeing him after this....

EDIT: We've had a lot of sex but I've never had an orgasm during these 8 months. it's not that he hasn't tried, I think it's because I'm subconsciously just not comfortable in our relationship...