I have a stuffed animal, Bear, that I'm overly attached to in the same way. So did my ex boyfriend. What can I say? We liked childish things. I know it was odd, but it was also a whimsical kind of thing. But we understood quite clearly that they were not real and not on the level of a human being. I think where the OP's post gets weird is that his girlfriend seems to include the stuffie in everything. Like, I definitely fall asleep with with Bear when I'm alone but when my boyfriend came over Bear slept at the end of the bed or on the floor or whatever. And he understood about Bear! If he hadn't had his own stuffie you bet Bear would would not be acknowledged or mentioned in his presence. Why would I bother? Even with my boyfriend, our stuffies pretty much stayed in the bedroom, and they only very occasionally and jokingly got involved in our day to day lives. Does get me wrong. I adore Bear and if my house was on fire I'd save myself, my dog, and her, hands down (assuming no other people were in the house). But she has no permanent, conspicuous place in my general life.

OP, I'll be honest, I do feel guilty if I ignore Bear for a long time or don't bring her on a trip or leave her on the floor while I sleep, and I wonder if your girlfriend feels something similar. A suggestion: when I start feeling irrational things like that I counter them with telling myself that she's off adventuring on her own. It's my imagination, I can make it whatever I want. I feel better when I imagine that Bear has a life outside of me, y'know? Instead of being like a pet, completely reliant on my attention.

This was a weird fucking post to write. I'm a normal, sane human being, I promise. I just have an incredibly active imagination and I see no harm in it.