so. noboru and shigeo's dynamic. let's talk about their feelings.
let's start with shigeo.
at first, he hated noboru, thinking he was a fool for making the wish he did. he wondered what kind of dumbass would make a wish that would prevent him from fighting the witches that he was tasked with fighting. he considered noboru to be useless, as someone who couldn't even see witches, and tried to pick a fight with him upon their first meeting. he continued to pick fights with him a lot.
but then..... as time went on, the two of them grew closer, and the fights shigeo would pick with noboru lessened quite considerably. if anything, he became more protective over him. subconsciously, he grew attached to noboru, constantly fretting over his wellbeing.
it took shigeo a long time to realize that he was actually in love with noboru, and when he did realize it... he didn't know how to feel about it. firstly, he hadn't realized he was gay to begin with, and secondly... how was he supposed to tell noboru about it? how was he supposed to allow that idiot to witness such vulnerability, knowing that he could very well betray him in the future? letting others into his heart felt like a death sentence to shigeo, sealing his own fate just like he had by making a contract with kyubey in the first place.
as time goes on, shigeo's debilitating crush begins to break him, adding onto the usual despair felt after fighting witch after witch. his soul gem darkens, he enters fight after fight without stopping, he takes out his anger on the monsters they signed up to kill without knowing the truth about the origins of witches... but when he finds out that witches used to be magical girls and boys.... it shatters him.
shigeo witches out in front of noboru. red cracks form in his blackened soul gem before it shatters, and with tears running down his face, he dies and is reborn as the witch of betrayal.
and all in all, shigeo never gets to tell noboru how he truly feels.
as for noboru.....
noboru fell for shigeo at first sight, but swallowed those feelings and refused to let them show. he's scared that shigeo will just push him away, or worse, think that he's some kind of monster for liking him that way. and he wouldn't blame shigeo if he did feel that way.
after all... noboru is weak. he can't see any witches at all (except for one, but... we'll get into that) and all he can do is guide the other members of their team into the fray. it's not like he can actually help in a fight, and he wouldn't be surprised if shigeo thought he was worthless for that. his heart hurt every time he saw shigeo, but he couldn't tell him why. he couldn't bring himself to tell him the truth.
and then... shigeo witches out in front of him.
because shigeo's rebirth as a witch is a natural progression given his status as a magical boy... noboru can see him. he can see what despair does to a person, he can finally understand what they're fighting. and it breaks his heart knowing that they've been fighting their own kind this whole time. he feels awful that his own actions have blinded him for so long, that his foolish wish led to ignorance.
that blissful ignorance led to the loss of the one he loved the most.
so... who fell first, and who fell harder?
noboru fell first, but shigeo fell harder.
shigeo cannot love normally, he loves like a dog who bites to show its love, he needs to be muzzled before his love is too much, before he goes too far and drives noboru away. he has to suppress his love for noboru so that he doesn't hurt him in the process, but it still slips out in the subtlest of ways. it's a miracle that noboru didn't notice it.