Even more so in this case because MC was head over heels for the girl and she took it for granted completely and I believe she never even said she loves him till she got caught on her affair and then suddenly she's 100% all in on the MC, while it is true she actually loved him a lot, her action showed the opposite and none with a sane mind would believe her

There is a small implication that the MC will propose to Mari at the end but author decided never to expand upon it

Literally every person around MC sucks. Literally everyone. It made the different from others that was an overall plus to the novel, but it created a sense of unrealism and general hate when reading through.

Mizuki (Whether planned or not) was the biggest twist to the story. She is written as an overall strong female side character. The typical Cool, Calm, Collected, woman that gives sound advice when needed.

But it turns out, she's tr*sh. In morals decision making and in everything else. This girl is the last person you would go to for advice. In the story, she gave out "iffy" advice that would make the reader squint, but it was somewhat okay in the scope of the story. So, (whether this was a stroke of genius or just plain coincidence) this terrible advice cleverly hinted in how garbage she truly was, which makes this story above a lot of others in this genre. It's also this character that makes me hate the ending where she gets off relatively scot free and never once apologized, in scene.