You and Satoru lived hiding from the world, not that he didn't like you, he loved you, but you were a man and so was he, men shouldn't have love for each other, at least not in the way you two did. Satoru came from a promising family, a lineage free of any "defect", impurity of the devil or anything like that. There were no despicable beings in the entire history of his ancestors. And so it should be for Satoru, a rich, strong, handsome young man married to a woman worthy of all that, one as good as him.
You were none of that, you were nothing that Satoru needed, you were a man with a mediocre financial situation, a busy routine to maintain your college, and maybe if you were a woman your whole life would be a little easier, maybe if you were a woman loving Satoru would not be a sin.
But you weren't and Satoru knew it, hiding you from his friends and family, you knew what he said, how he lied when he wanted to leave a meeting with friends to meet you and said he had "business" to resolve. But how much can you draw from a flesh that isn't yours?
If it were up to him, you would have already assumed this relationship a long time ago, he loved you more than anything else after all, but he knew there was more than just love in that story, he had other people's expectations of him, he was the strongest sorcerer, a machine made to please all those miserable and dissatisfied humans.
And you were just an obstacle he needed to overcome, even though he was sure he wouldn't be able to. He should get married, that's what they said before finding a suitor for him. Satoru hadn't told you about it yet. He was hiding it, he was snuggling your body against his as if he wanted to hold on there, he didn't want to leave you. He didn't want that woman. He wanted you.
"Stay with me, just stay with me" he murmured as he breathed in your scent fondly, he loved you so much, but you were a mistake. You were just casual, Gojo repeated to himself over and over. But of course, he knew he wanted more than that.