I feel there's three possible points people who defend Nanase miss:
1 - I feel one reason some "defend" Yuni is because in the beginning the Yuni hate felt really overblown at times, like, I honestly don't think anyone will argue against the cheating being bad but some people talked about her as if she was some unrepentant sociopathic monster who was cheating for the lulz cause she's eeeeeevil instead of literally being a dumb teenager who also has quite a few problems
Sometimes it also felt like some people put Nanase on a pedestal as the poor little victim who could do no wrong, arguably the same for Yuki which is why some wanted them to get together, they were the good guys while Yuni was the eeeeevil cheater who deserved to suffer
I say "defend" cause in my opinion a lot of the time it's less actually defending Yuni and simply arguing against the exagerated caricature some created of her, which funnily enough became easier and easier as the story progress and we see Nanase isn't really all that
2 - I think one thing some miss is that yes, Yuni, Fuuko and Yuki sucks but that just because Nanase sucks less that doesn't mean she doesn't suck, this is not a competition really, Nanase just sucks in a more mudane and arguably more infuriating way, hear me out:
Yuni: we see again and again that mentally and emotionally she's not exactly the most stable and has her own issues, honestly she arguably shouldn't be in a relationship to begin with lol, but at the same time we see that many times she openly admits to herself what she is doing is bad and should stop, of course she doesn't and emotionally is all over the place so she still sucks but she still cknowledges that she is bad
Fuuko: she's the most honest of all, she never denied she's bad, if anything she openly embraces really, of course that doesn't change the fact that she sucks just because she's honest about what she does
Yuki: she is arguably in my opinion the most malicious of them cause she acts like she's good but did some pretty bad stuff without any remorse, I honestly doubt she feels an ounce of guilt for the pain she caused Nanase but hey, she got Nanase on her side so everything was ok in her head
and then comes Nanase, she is arguably the only "good" person, nothing she does is really malicious, like, we saw little by little she was a shitty girlfriend, kinda neglicent, insensitive and so on but we couldn't really give her much shit cause she's literally just a dumb teenager making dumb decisions, it could be frustrating but it was understandable
At least until she finds out the cheating that is, she chose to continue with Yuni and promised to get better but what we get? She repeating the same mistakes even after communicating with Yuni, she never really listen or relate to Yuni and continues to be negligent, insensitve, self centered, she makes her assumptions like about Yuni mother or her maybe now being interested in tennis and rolls with it, or leaves Yuni alone even after she said she didn't want to be left alone, there's various examples really
We were able to excuse Nanase behavior cause before it was just a clueless dumb teenager doing innocent mistakes but after she promised to get better and clearly didn't change at all it goes from frustrating to infuriating that she's making the same mistakes all over again
Nanase is basically the classic "no thoughts, head empty" meme unless it's about the club, even when Nanase and Yuni communicate she still doesn't listen and doesn't change at all, I suspect that for some people the exact fact that she's not malicious about that just makes it worse, especially for people who had to deal with someone who just doesn't listen and never learn or change
I feel this chapter really settles how Nanase is those things cause Yuki world just collapsed from finding out Nanase never really saw her as her bestie lol, depending on what next chapter shows it's pretty much the last nail that yes Nanase is negligent, insensitive, self centered and so on and can't think of anything but her little world that is entirely focused on the club
3 - last but not least, cheating aside I feel Yuni, Fuuko and Nanase can feel a little too dramatic compared to Nanase, Yuni is a mess, Fuuko is too openly evil wanting to steal Yuni, Yuki is two faced bitch and her attitude can be hard to take seriously, Nanase meanwhile is just too mundane
Still wanting to be with Yuni aside since that can feel unrealistic then Nanase attitude as a whole is too normal, too mundane, banal, she's not a bitch, she's not malicious, she's not evil or anything like that, she's just an airhead too focused on the club that she completely miss everything else, she can be called selfish and insensitive but that's pretty on brand for a teenager really
Until she decided to still be with Yuni after knowing about the cheating, that completely change context of things cause after promising to change she just don't change at all, I can't help but feel that for some people it hits too close home, Yuni, Fuuko and Yuki can feel too unrealistic while Nanase we can pretty easily find many people like her
Honestly? I feel that if Nanase was as bad as everyone else nobody would bat an eye at it but it's exactly the lack of malice and the mundanity / banality of how she sucks that ironically can make her feel like worse than she is, the way she sucks is just too relatable, the more you had to deal with people like her the worse you'll feel about her as a whole
We can argue all we want about how Yuni, Fuuko and Yuki sucks and who's the worst or how Nanase sucks the least but the fact that her brand of suckness is so mundane can feel too personal while the others feel too much like typical dramatic romance, her mundanity ironically stands out like a sore thumb exactly because you can easily meet people like her, worst, might have or had a relationship with someone like her who never listen or changes and they're just, ugh, the worst
Anyway, at least that's my take on why some people "defend" Yuni or at least bashes Nanase, no amount of "b-but the others are worse" will change that Nanase still plain sucks
