I feel like a lot of people are underestimating how draining cosplay can be? Marin is a total extrovert and feeds on the energy around her but her most important person, who put a lot of pressure on himself and her to make this cosplay perfect, had almost no reaction after. This is a total flip compared to how he has reacted in the past and has Marin off-kilter. She doesn't know what's going on with him and doesn't know how to react in response.
We've seen in previous chapters that she has a social intelligence and is entirely okay with not being liked by people, she knows she's a lot and she knows that she can rub people the wrong way. But when this person who she is majorly infatuated with, someone who she has gotten extremely close to, suddenly shuts down and withdraws into himself after what she thought was a major accomplishment? I also would be unsure how to react in response.
Plus she clearly is seeing him the literal next day and (based on my understanding of the translation) I got the vibe that if he was still in that funk she would have said something. But he was (seemingly) back to normal, they are not alone in the space, and she is (probably) tired and still processing everything from the day before and online.
Also she's what, 16? Please give her some slack for any lack of communication skills.
This wasn't something that I was going to go into, but as a lot of comments are playing the blame game I'd like to come to the TEENAGERS defense a bit.
I'd like to mention that Marin constantly offers to help Gojo. She was going to several different fabric stores looking for him, she offers to cook, she legitimately tries continuously to be of help. It is NOT Marin's fault that Gojo (and others) do not take the time to explain
why things she does concerns them. They make leading comments or ask leading questions but never confront her on things like her cooking. They never say 'hey thats a lot of protein and grease, maybe add some more vegetables to that?' She is currently on a diet, and sticking to it, and is clearly able to follow directions in this way, Gojo or his grandfather could offer to give her tips or lessons!
Same with sewing. I know this is from waaaaay back in the beginning but just reading how to do things is different from doing them. Otherwise everyone could fly a plane from reading the manual. Gojo could involve Marin more in the creation process (as she has offered to help several times) and teach her. The finished project may not be as perfect but Marin has shown joy in helping in the process before, so clearly it would not be a hardship!
On Gojo's side his severe lack of social intelligence and experience is hindering him, plus his severe self-esteem issues (seeming to border on imposter syndrome at times) means that everything he does is weighed against his own delusional expectations of self. Gojo is a clear introvert, even as Marin (somewhat forcibly) worms her way into his inner sphere. He is shown regularly to have difficulty speaking his mind, even as he is improving, unless it is in a 'professional' situation. Any major issues that he is experiencing, cosplay or personal or doll making, is shown to be something Gojo thinks he has to deal with himself. Gojo is one of those unfortunately relatable characters who gives great advice on asking others for help and offering support but never seems to follow it himself.
In regard to his 'eureka' moment at the event, we have yet to been explicitly told what he realized. We think that he realized he is in love with Marin, but it could be something else entirely. Thus far we have seen Marin realize and get advice from her friends in a round about way on how she ought to move forward with her feelings. Gojo has not done any of this yet. Marin is valid in not confessing if she has no reason to think Gojo reciprocates. Gojo has shown emotional attachment and investment in Marin, but he has not explicitly told us that he is in love with her. There have been showings of sexual attraction and him getting flustered around her, but that does not equate being
in love with Marin. He has come a long way in terms emotional maturity and experience but he is very much not mentally there (at least not consciously). We the audience see that he cares for her, that he likely has at least a crush on her, but he thus far has almost only expressed admiration for her as a person, not as a romantic interest. Also, I say again, he/they are teenage age. I know I was not a skilled communicatory at that age, and as such can understand why they make these choices.
Unfortunately, as much as this manga is a duet of perspectives, Marin and Gojo are within two different mangas. Marin is in a shoujo (possibly josei) romance themed manga and Gojo is in a shounen/seinen professional development (I will be the best/accomplish my dreams) themed manga. The characters interact and react to each other appropriately based on these genres. For Marin the romance is main plot line, while for Gojo the work is. Their secondary plot lines are their opposites major plot lines. While this is great for balance purposes it does cause conflict at times.
Also thank you to the scanlator teams who work so hard to release the chapters so quickly. I love this manga and would likely die a little inside if I had to wait for each volume's release alone. ❤️