Problem wih baby name... My BF wants it to be connected with his other kids?

My boyfriend of 11 years ( on and off) wants to give the baby the middle name of Marie... He has 4 children 3 boys that all of their names are connected, and 1 girl (that he had while kinda on a break from me) and her middle name is marie. I don't want that connection but how do I say that with out making him really mad?