Maybe she's not comfortable with that kind of public display of affection or has some personal reasons.
The girl might push away because she doesn't know the couple, or she could be opposed to public displays of affection in general. It's hard to say for sure without more context about the situation and the characters.
It could be that the girl has different feelings about the couple or is in a bad mood herself. There are various possibilities. Maybe she doesn't like the couple or maybe she's just having a rough day and doesn't want to be around such a scene.
Maybe he's having a bad mood or there's some misunderstanding between them.
The guy might push the girl away because he's scared of commitment or has some unresolved problems from his past that are affecting his actions in the present.
Often, it's the unexpectedness of the push-away action or the character's expression that adds the humor. Also, it could be that it breaks the normal pattern and catches us off guard, making us laugh.
Maybe she's trying to get fit or build strength.
A memorable cartoon couple's funny love push often involves unexpected elements. It could be a funny misunderstanding that leads to a cute resolution or a comical situation that brings them closer. Also, the expressions and body language of the couple can add to the charm.
Perhaps it's to introduce a conflict or a lesson. Maybe the girl needed to face a challenge or overcome a fear related to water. The reason really depends on how the story unfolds in the cartoon.
The boy might push the girl accidentally or it could be a part of a humorous scene. Without more details about the cartoon, it's hard to say for sure.
She might use proper form, starting with hands on the ground and keeping her body straight as she lowers and raises.
Maybe the big man was trying to protect himself or was in a bad mood and acted impulsively.
Maybe the girl was under the influence of some magic or mind control in the cartoon world. Or it could be a dream sequence where anything can happen without rational explanation.