Kink: transformation, bad end
By the time your girlfriend manages to find the potion to turn you back to human, it's already too late. You regressed too much. You have enough human mind to communicate, but just that. You don't remember your love for her. You barely even remember her name. You feel much more comfortable as a rat in a cage than you'd ever be as a human.
re: Kink: transformation, bad end
@arina_artemis A sufficient substitute.