Name game advice

Help! Boyfriend is hell bent on naming our son after himself, making him a Jr. My one rule has always been that whatever I name my son, he WONT be a Jr. We are having twins - boy and a girl. He gives up all rights to naming the girl. I've dreamt of naming kids my whole life, and I'm only doing this one time, not having more kids after this. I always imagined my son to have a strong name that I love. I'm not trying to be selfish, but he really won't budge. I've tried giving him the option of using his first name as our sons middle name, or at the very least, changing the middle name to something else. He just seems horribly offended every time I bring it up. But we are half way to term, and really need to agree on something soon. Advice anyone?