Bro didn't even know he was a fuckin rabbit until recently, of course he has no attachment to it.
Mom's an idiot, and an ass, for trying to make him have doubts about his relationship just because his GF might fall out of love if he loses his rabbit charm. That's not an argument to make to begin with because he's not going to the moon regardless.
And anyways, where's she coming off having any opinions to share after pumping him out and dumpin him on earth. Voyeurism isn't being a parental figure, dumbass.