The Cute Doll Game Over is an ending which occurs when Eric(a) fails to resist at least two times during the fifth tea party with Alice when she gifts them a doll mask.
During the tea party, Alice shows Eric(a) a realistic-looking ceramic mask, which she promptly forces onto their face. After it adjusts itself a little and fuses in place, they can hear the other dolls talk. Since the mask is also a mind control device, Eric(a) unfortunately cannot talk on their own nor run away. Alice proceeds to describe her philosophy, and Eric(a) has several moments to try to actively resist, but ultimately it would prove futile. So Alice finally commands them to be happy, and for no apparent reason they are. Thus they lose themself in the role as Alice's new beautiful doll friend.
While outwardly continuing to seem normal, the act immediately drops once they are alone with Alice. Maybe someone will eventually rescue them from their fate, but what would remain of Eric(a) by this point beyond a happy mindless doll is anyone's guess.