BF/his friends. Does he want to marry me cause of my butt?

Alex • 25, ABD&OB/GYN RDMS
So my boyfriend recently got into a whole new friend group (which are awesome people). These are the kind of friends he has always needed in his life and both me and him enjoy this group of people so much. They are so nice and funny and easy to get along with.
So among the people I know, I am kinda known for my big butt and wide hips. I can hide it very well and sometimes I can't. Well the first few times I've met his guy friends they commented to my BF how cool I was etc etc which was nice I loved that they approved of me. The other night we went bowling as a group and I happened to be wearing some Capri workout pants and a t shirt. I guess this is when his friends realized I had a big butt. My BF told me when we left that they said I have "major curves" and "no wonder he always stands behind me" and something along the lines that "he got the full package, congrats."
My BF has always mentioned he wants to marry me but that night after his friends told him stuff about me he just went on this huge happy rant over saying he wants to marry me  so bad or atleast get engaged. He was all like so how can I get a ring can I get a loan?
My point is maybe I'm overthinking but is he all honkydorry now cause his friends think I'm good-looking? I mentioned to him I hope he isn't saying all that cause of the way I look and I hope he would do it cause he truly loves me. He said he is.
I guess the fact other guess notice me reminds him I'm a catch? What do y'all think? I don't want him to marry me for my ass.