it's not as bad when there was this high school girl having a crush on him, but just a moment ago I just realized she was a pedo (I have a fish brain) :'> now that changes everything like what in actual heck is the author trying to do? I legit just felt sorry for her before remembering what she did.
your point was using this pedo character as a new challenge for the main couple right? My argue was the author could have chosen any other character, like in the past the same high school girl and reappearing in the story would have been fine by me, or a new love rival would have been also fine, but instead they're trying to make a pedo look bad and sympathizing, almost to a state of sorry. And the way every character like the main couple react it was peachy and fine cuz it was long time ago also makes me feel weird, like it's a normal thing to do.
anyway, I think it was a poor decision and in my humble opinion the story seems better without her.

the people having problems with other characters getting introduced is so weird it's not like every character they introduced were love interests, it always ended up not being the case and they were mostly used as plot devices for different kinds of resolutions for the couple. it's not like it's a repetitive case of just misunderstanding about a third party
and the fights they had aren't even that bad. they always resolve it with so much understanding and talks. it's the usual human mind that overthinks and hesitates before confronting and they have it better than most cause they solve it way faster without much conflict. it's very realistic and yall are just exaggerating the severity of it all.
i wonder if yall are the type to think that a relationship should be perfect to a tee or else it's "tiring" and "not ideal"