The male protagonist's setting is imaginary (maybe a bit yandere)
The heroine is a helpful, brainless, natural scumbag who easily likes the new and dislikes the old. She is very popular in three minutes.
The male protagonist was deceived by her. He was deceived about everything. When he found out that the female protagonist didn't like him, he was very desperate. That's it.
The setting should be male c, female and him c, but there is someone else behind.
Wait until the next moon, I will give up on you (I guess this means)
Concept: Society is sinister and people's hearts are complicated