I haven't learned very much from manga, but what I have learned is that you should never, ever date a Japanese girl.
Ever.
FUCK ASU. Her design is cool but goddamn she’s such an asshole for siding with Jason. Really irredeemable. That was not a misunderstanding. And the MC just took it on the nose, Jesus Christ. I’m glad he at least firmly said he isn’t coming back. But man that really did ruin the character for me.
Thanks for the translation! Demon girl is best as always.
Background Thoughts
Different idea of an "ideal female" vs the West. Ideal is a woman who is possessive and will contest other women to get ML. (Consider the number of stories where there's a nice, not-so-aggressive girl contesting for the ML -- they almost always lose because they don't fit the ideal.)
Though another factor is whole "social reticence" where characters have to go through multiple volumes before they will admit they care about the other character. (Complemented by the "I waited too long to confess and thus missed my chance!" trope.)
Also JP is more explicit about the "If they guy is a good catch, then there's got to be a bunch of women chasing him." Hence from the female PoV you get "romance combat" i.e. the thrill of the fight to get the top man.
Single beauty/attrractiveness standard. The West leans much more towards varied beauty/attractiveness standards.
From male PoV, the ML gets a harem without trying. And has to be oblivious to it in order to avoid committing and thus cheating.
Herbivore man: ML is not sexually aggressive. Standard JP trope.
Of course, from plot PoV, the romcom plot is finished as soon as mutual love is recognized & committed.
As Applied Here
Always have to have a female member of the kicking party be against the kick because she's secretly attracted to the ML. (Here it's excused because she wasn't present at the time of the kick, and thus didn't get a chance to veto it.)
Harem building, competition for top male, oblivious ML -- standard tropes that work together.
Extreme possessiveness. West would (mostly) view that negatively, but it's pretty standard in JP lit.
Also, note that we have a standard childhood trio (2 boys, 1 girl) -- gives the girl the chance to have a mini-harem and play eenie-meenie-miney-moe with them.