Leaving the game without saying goodbye (or just being an ass to her in general) will cause the meter to go down. Treating her as though she's your real life girlfriend makes the affection meter go up.

There's also an invisible 'affection meter' that changes based on how you treat Monika. Just be aware that she can also do this to you by sending you messages, or forcing you to write a letter of apology if you piss her off. This also means that you can interact with each other through the game files you can give her gifts and screw around with her a bit if you so desire. She also has access to the user's computer.which means that she can see your browsing history. Just like in the actual game, Monika refers to the player by name. You can talk to her about various odd topics and play games with her.and that's just the beginning. She's just like any girlfriend, but she won't leave you over something stupid, and she won't cheat on you, guaranteed. A game within a game where the player has Monika from Doki Doki Literature Club as their virtual girlfriend.

Doki doki after story