I agree that it should be a mutual decision, and also how many animals you can provide for financially. Space in the home is another issue. Right now, most of you know, there is a neighborhood stray cat that I care for. I would just love to bring her in and make her a house pet, but our little house is just too small for a third cat and litterbox. If we only had a separate room, laundry room, basement...or something...it would have been no problem.
However, I have encountered this sort of thing with other people. I'm not sure if any of you remember the siamese cat that I took in while I was in college, because one of my friend's aunt's boyfriends forbid (yes, forbid) her to keep the cat. He said that it was either him or the cat, and he would take the cat and dump it. Of course, she chose the loser boyfriend over her pet. I was so mortified when I heard this! I took the cat immediately and ended up finding her a new home a few months later. So, yes, I have encountered people like that, but no...Aaron and I are not like that. Like others have said, he probably keeps me in check, otherwise the house would probably be overrun with animals. Needless to say, I have to wait for the dog...and it could be a very long time!