Yes, not mature of your boyfriend to make you choose. My husband and I lived in the same apartment complex, across the parking lot from one another and I started feeding a stray which he adamantly said I could not allow into his apartment (where I spent my time) but I absolutely could not leave it out in the cold (it was fall, going on winter) so I took it into my apartment. I was never there so it was not terribly well behaved by the time we bought a house and moved in together but it was "mine" and my husband took me and mine. It was not like he had to feed or care for it. He nicknamed it "piss off" as that was its (Rufus) attitude :-) But he let me be me and love whom I liked, etc., he did not try to change me to suit himself? Perhaps you need to use the cat as a way to look at the boyfriend differently. If he gives you ultimatums over a cat, what else might he try to take from you?