Why in the hell would you want or even wonder if your girlfriend cheating on you will be in this game.
Do you really want to play a game where your girlfriend could cheat on you? No, you don't. Stop being stupid, you don't.
YOU will be able to, but there will be concequences, but your GF cheating is illogical as there are a LARGE amount of datable options, and some characters would act differently than some.
The game is designed to be fun, real, but not stupid, so cheating is illogical.
Breaking up, though? That's a possibility.
If you don't hang out enough with them in certain intervals, it makes sense for them to break up with you. You made a commitment. This ain't persona. You can't fall in love then never hang out with them again.
The player may be able to break up with a girl, but that's debatable since it would be so much work to do.
Long story short:
If you make a commitment, see it through.
I agree. the game is meant to be a fun visual novel. A slice of life take on the Pokemon world and the game will be much more fun focusing on the interesting gameplay elements incorporating the Pokemon world into a school setting. And having the MC and Waifu choice build their relationship and test that relationship with Pokemon themed challenges.
red is also not a mean guy by nature, and most of the choices reflect that. Even the ones where he shrugs stuff off saying "This stuff is too easy!" even if it's egocentric, it isn't strictly mean. Red's a nice guy.
"Praise the one true ruler of all: The supreme being, the Sorcerer King Ainz Ooal Gown!"