Something I want to point out to all the people talking about how Gojo is taking the aftermath of the circle shoot. Look back at Chapter 61, all of it, then specifically Chapter 62 pages 10-12, moreso the expression he has on his face in the last panel of Chapter 62. He knows that he wants to support Marin no matter what. He also knows that he loves her, he just can't see himself standing by her side. As a support from afar, yes, but not by her side. This is referenced in Chapter 99 page 13. In Chapter 63 this is push out of the way by the classmates bringing him in, but once again in Chapter 78 page 21 the idea of him being there just as a support is reinforced.
Then at the end of Chapter 86 he finds an obsession: Haniel, and we find a hint of the source of that in the next chapter on page 18. Haniel reminds him of Marin, but he still can't admit it. We see him want this to be so good that he's even hyped himself to fight for his dreams in Chapter 93. We get a mirror of the message "It's finished. I'm going to sleep." from first costume made for Marin that initially connected them. Something Marin loved and wanted and Gojo made for her, but this time it is something her loves and wants and it is made for him.
We see from Marin's discussion with Gramps in Chapter 94 that other people see that Marin is good for Gojo because he can't love himself or what he does because of his perfectionism. We also have to remember his trauma which has been somewhat assuaged by Marin in the first arc and in the Rei-sama arc, but isn't fully dealt with.
In Chapter 99 things come to a head when he realizes he's in love with Marin. He knows it, but he also sees how he asked her to make other people fall in love with her, and that he doesn't just want to support her. He wants to be by her side. Then the moment that really connects what Gojo and Marin are each feeling: Chapter 100 page 20. There is now an ocean physically and mentally between them on how long this can go on. To him he is one of the crowd of humans that are lower than worms in love with Haniel who is Marin. In Chapter 96 page 20 it alludes to this: It isn't just love at first sight. It's a consuming, aching, terrible love that leads to obsession.
Chapter 76 Marin imagines how Gojo would respond to her confession and it begins to break her confidence, this becomes deeper in chapter 77, though by the end of it she's trying to psych herself back up, but we see that crack and on page 16-18 when she realizes she has real deep feelings. This isn't just a crush. This is real love and it makes her afraid of what will happen if she's rejected. Chapter 100 pages 20 has the first thought since then of "What if something puts a wedge between or breaks their bond? What if they can't do this together forever." And then from pages 21-27 she sees that distance growing and doesn't know how to bridge it.
The pacing is a problem because monthly and wanting things to happen, I get it. But this is a slow burn with call backs and build up over multi arcs that is coming to a head.
Please reread and try to look for it. It's even somewhat in the nun arc.