Although the user you're replying to hasn't played the full game,
Has anyone? The incomplete game is all we can judge. And what we have in the incomplete game is miss perfect being a subservient doormat to a cartoonish douchebag for no reason other than a vague allusion to the length of their relationship.
It feels like a shallow version of the already shallow "girls like assholes" cliché. I wish we had left that one back in the previous millenium.
I don't mind the MC simping for her despite that because the MC is portrayed in the past as hopeful and innocent and the current MC is still a hopeless pervert (
sigh) and a purposeless loser currently failing at life. Desperation and nostalgia would keep the MC trapped in that silly crush.
I like the idea of our protagonist improving his/her life to the point where she/he's more attractive than the "rival". But when the bar to clear is not only on the floor but subterranean that's so much less interesting.
For this to not be as dissatisfying in the future it will need to be addressed. Maybe the new and improved MC with better self-esteem realizes how sad it is to be after that girl. Maybe the shallow caricature of a gaping asshole that is Diana's boyfriend gets humanized a little and we get valid reasons why their relationship exists at all.
Flawed characters are great when the story is aware of their flaws. At the moment, we don't have much reason to believe the story is aware of Diana's and Lu's.