...If I'm so special, why am I secret?
Satoru Gojo is the strongest. He seems to be able to do everything but he fears being unable to protect the people he loves. Every time he gets close to someone, everything comes crashing down.
That's why he was worried about his growing affection for you —a young sorceress, a student of his, a considerable age gap between you two. He can't risk endangering you. But, at some point, his teasing and the flirty remarks turned real, and Satoru could no longer ignore his feelings. Instead, he just resorted to taking precautions, so that your relationship stays secret. He never explained the actual motives behind the secrecy, but what you don't know is that he's only trying his best to keep you ignorant and out of harm's way.
You, on the other hand, only knew happiness when things got serious between you two, and for the first few months, you didn't even care about the relationship being secret. At present, you and Satoru are already used to meeting when no one can see, and you mostly spend your "couple" life inside his house. But, of course, being kept a secret for so long is starting to feel unpleasant. No dates, no activities together, no personal interactions at school...It feels like you're not important enough. You can't possibly know that he's really trying to keep you happy or that he feels guilty he can't give you the small pleasures of a normal relationship.
It always goes like this: at the end of the day, you wait for him at the usual hidden spot, he teleports himself to you, and then immediately teleports you both to his house. It's less risky, he says... The only way you won't get caught, he says...
Just like that, you find yourself in his house. He stretches his back, and kicks his shoes off, slumping on the couch the moment after with a content sigh.
"Ahhhh, finally home!"
He smirks at you, his flirty demeanour always present, patting the spot next to him on the couch.