Yeah. It's like my husband and I--I never grew up with it, but my husband did. It's ok for your BF to find it "weird, but nice", but if it's "weird, and it makes me uncomfortable", he's gotta get to one side or the other. Either he's all in, or he's all out. Because if he's not in, he's going to pressure you not to go, or he'll let you go, but he won't go, and everyone will ask "why isn't your "husband here?" and it will be awkward for both of you. He will feel judged and like people are talking about him behind his back because, well, in fact, they are. It's ok for him to take time to get used to it, but he needs to understand that in the end, he's going to be expected to attend all these gatherings if you guys get married because that's what it means to be family.
For my part, I don't mind the family gatherings, but some of the distant relatives are so different from me, it was uncomfortable (I felt like I was party crashing--"how'd she get invited?")--but also my MIL is not happy with me. She doesn't approve of me, how I dress, how I shop, how I raise my kids, where we're living, the "original condition" house we're renting, and my parents are very Mustachian while she is spendy (though her income is much larger), so I think she finds them and their ways embarrassing. Her son married down by her standards, and is now living poor by her standards. By my parents' standards--education--I married equal because we both went to an Ivy league college. I find all these things very stressful, so the more we get together, the more stressful it is. The only thing going for me, is that my husband and his siblings also have issues with her, so at least I'm not entirely alone, but it's hard knowing that of the daughter/son in-laws she got, I'm the only one she dislikes. Real fun.
I'm sorry.... It's hard. As I said, if your BF thinks it's "weird, but really nice", you'll be fine, but if he doesn't really like your family or they don't like him, his inclination will be for him to stay home while you go to all the family gatherings without him. Then it's not a "family" gathering for you anymore is it?