Within the confines of the characters as written, I guess I can see the MMC as a fallible dude who wants to be the good guy. FMC as misunderstood good gal with her own human struggles, also okay. The Olympic-level mental gymnastics required to shoehorn the series' central conceit really strains my much-abused suspension of disbelief though.
The author's writing and character concepts are what you get after spending too much time reading within one narrow genre, and neglecting to diversify both your RL experiences and reading quality writing in multiple genres. Way too narrow and derivative. Second-rate characters tend to talk too much about "the relationship" in a vacuum or whatever surface activity they're doing together, because the author doesn't know how to write more extensive interactions and reactions to the environment around the characters.
Good writing requires an author to be willing to kill their darlings sometimes. Not literally, but don't coddle the characters. Let them experience real challenges and changes organically, instead of contriving neatly resolved cookie-cutter "problems" every time. This criticism applies to a lot of manga/LNs in every genre, not just this particular manga.
After several decades walking this earth, I pride myself on having occasionally escaped the darkness of my parents' basement -- and even on occasion talked to a woman. (/sarcasm) It really doesn't take much exposure to get some sense for how people talk, think, and are motivated to do what they do right or wrong. A few weeks to months of building a relationship of any sort can provide more insight and depth into characters than what's written in series like this one.
Some authors really manage to capture elements of verisimilitude in their characters' dialogue and choices. Romcom, isekai, drama, gritty war-is-hell -- every genre has good examples. And taking the last one as a specific and extreme example, at this far remove from devastating wars involving Japan, it's clear that some writers are able to grasp the human condition through others' accounts without having to experience some kinds of trauma firsthand. If an author today can write something like 86, then there's no excuse for far more authors to be unable to write better romcoms using far more accessible daily human experiences.
I do appreciate that the author innately wants to write the MCs as nice people, as opposed to the uncomfortable, edgy revenge pr0n in some series. I wish them luck on their next project and another few years' experience in RL and in reading stuff outside this genre though.