Why did the manga fat girl eat her boyfriend?

It could be that she met someone who seemed more exciting or offered something her current boyfriend didn't. Maybe she's going through a personal crisis and makes a bad choice.

Maybe she was jealous. Jealousy can make people act strangely, and in this case, the girl might have felt threatened by the presence of the other pretty girl near her boyfriend.

The reason might be to raise awareness about body positivity or to add an element of surprise and contrast in the story. It could also be that the artist wanted to explore different representations of femininity and beauty.

It could be due to various reasons. Maybe the ugly guy has some unique qualities that the girl values more than looks. Or there might be issues in the girl's relationship with her boyfriend that led her to make this choice.

Maybe the boyfriend did something unexpected or threatening that scared the girl.

Maybe they had a big fight and he said something hurtful.

It could be that the cartoon emphasizes the physical and emotional toll the rescue takes on the girl, leading to her weight gain. Maybe there are scenes of her eating more due to stress or not having time for exercise.

Maybe she was driven by extreme emotions like betrayal or abuse. Or it could be a result of some deep-seated psychological issues.

Maybe he did something wrong or didn't understand her feelings.