You can't literally expect the other person to keep doting on you forever sure she forgot their anniversary which is wrong but she has a life to focus on which doesn't revolve around her girlfriend, Yuni herself realizes this since she says that she should've called her herself rather than expecting Nanase to do it coz she did it for the past 5 months.
She just got an opportunity to play as a starter which is a big thing for her plus you're 6months into dating, if there is something you're not satisfied with talk it out or break up, Yuni does that in chapter 4 but in chapter 5 she goes back to the old self who desires affection and care which she doesn't even acknowledge that she did something wrong instead she blames Nanase or Fuuko for it.
Well again she is a highschool girl with her first relationship so I don't blame her but I don't think Nanase is playing with her either, I may sound biased since I read the raws but even before that I don't think Nanase is a complete b!tch with no regards for Yuni's feeling
In a relationship where the only time you get to "be in a relationship" is behind closed doors and away from other people (which as we're aware is Nanase's idea), I'd think every bit of affection that they can get matters. And in this, Nanase is not holding up her end of the relationship as well as she could be. And again, as stated, it didn't even need to be anything more than a phone call. Just some time, that Nanase put off so long that Yuni was sure she'd forgotten. It's not "revolving around her girlfriend," it's giving the person who's supposed to be important to you the attention they deserve, on a day where that attention is all the more meaningful.
Sure Nanase wants to keep their relationship a secret and even a 5min call during their anniversary is all Yuni needed, but Yuni knew that Nanase will be busy with her club duties and expecting the other person to take the initiative everytime is kinda ridiculous and Nanase has said why she wants it to be secret coz she doesn't have fond memories of even having a crush back in middle school, just some "trust me and kiss" isn't going to make it all go away.
She forgot the anniversary sure it's wrong but it's realistic, and it's not like she was spending time with a side chick or a girl who said that she is fine being her 2nd girlfriend.
Nanase prioritizes her club very much and Yuni knows that so if there is something she is not satisfied with she ought to outright say like she did in chapter 4.
Nanase as a girlfriend is hard and dumb as brick but she actually talks about it rather than keeping it bottled.
We as readers know Yuni is frustrated with lack of affection coz she blows it on her alt acc but Nanase doesn't read or know what Yuni exactly wants.
Yuni has kinda made a idealized image of Nanase being the perfect girlfriend and when something she doesn't expect happens, it makes her upset.
Next chapter Nanase realizes that she actually needs to show affection to Yuni and even says how she is dating a girl to yuki.
Yuni on the other hand gets a text from nanase saying different than usual to picture she sent(which is actually very different since she just cropped fuuko out of it and is blushing very furiously) and gets disappointed like bruh.
I assume you caught up to the newest raws so I will talk about spoilers.
Yes. Yuni has a lot of problems, but that doesn't mean what Nanase doing is right. Nanase doesn't understand what being in a relationship means, and only does things convenient for herself. She tries to make Yuni happy by buying Yuni a juice, but she got the flavor wrong. She knows their relationship is still tense from her forgetting the anniversary, but she was still going on and on about volleyball, with Yuni looking bored and not able to say anything
I was happy when I saw Nanase telling her friend about her relationship and was beginning to come out of the closet. I thought she was finally going to change for the better. Then she immediately tells Yuni to travel to another city Osaka to watch her match next week. She is not even asking for Yuni's thoughts on it, but pressures Yuni into agreeing to come. "I really look forward to it. You will come right? You can also do some sightseeing too, ALONE." That is not how you ask your partner for something like this. Sure, Nanase is going with the team so she doesn't have to pay travel expenses or worry about her safety, but what about Yuni? Yuni has to pay for her own trip and she doesn't have the money, and it is dangerous for a high school girl to travel alone, but none of these even crossed Nanase's mind. She just tells Yuni to come and that's it. Yuni is so desperate that she has to rely on Fukko's money.
As for the photo, can you really blame Yuni for being mad? Yuni went all the way to Osaka to watch Nanase match. She texted to Nanase "Are you awake? How's your day? How do I look?" with the photo. The only reply was single phrase "You look different today." At lease ask about Yuni's day and tell Yuni about hers for god's sake. If Nanase is going to bed early for the match tomorrow, she can tell Yuni about it and say good night. Nanase did none of these and just went with the one-liner to end the conversation. She is the one the asked Yuni to come but she doesn't even seem to care about how Yuni is doing.
Nanase doesn't need to give up volleyball or anything, she just need to give some thoughts to how Yuni feels, and sadly, she is not doing it at all. Even if we let everything else slide, at the very least Nanase should know it is hard for her girlfriend to spend a large sum of money to go to Osaka to watch her match alone. It should be common sense if Nanase has any consideration for Yuni, but she just takes everything for granted.
Never said Nanase is the perfect girlfriend either.
Most of the stuff I've mentioned was the problems with Yuni with the updated chapters not the raws.
That whole rambling was about Yuni having "unrealistic standards" comment with expectations and not being understanding about their relationship.
Plus I did mention about Nanase being a dumb girlfriend.
As much as I think Nanase is in the wrong I feel Yuni's lack of communication with nanase makes it worse than it should be.
Leaving your girl alone at Osaka sure that's not right but at the same time Yuni never says her side of stories to Nanase, Fuuko is convenient to Yuni but having a girlfriend and hanging with a girl dead set on becoming your 2nd girlfriend (not completely) is wrong in itself, chapter 8 and 9 makes Nanase a dumb girlfriend which takes things for granted but there are moments when she tries to be with Yuni, in the same chapter she even invites Yuni the next time but that gets interuppted by Fuuko. Yuni is in relationship with nanase for the 6th month and she literally wants to be showered in affection all the time not trying to be understanding or speaking out about the stuff she is not satisfied with.
Ik when I included spoilers I should have spoken with the context and not vague but that still doesn't make Yuni any better than Nanase.