Just my opinion. I think Itsuki just didn't want to give Yuusei any way out of it. So he tried to really push his limits into admitting his feelings himself. He tried to let Yusei feel his presence all the time. If he confronted him then and there he would have just denied it again and run away believing his feelings were not normal or maybe one-sided. Seeing their reactions I believe Itsuki is the one actually chasing Yuusei all along.
I don't think yuusei will denied tho, like yuusei said he warned itsuki to not pushing him because he will attack him he will kiss him and itsuki keep pushing he know yuusei will do it if he keep pushing. It's take so much push for yuusei to do it yet after he did it, itsuki being cold to him. Did not stopping him when he go out from the room and the next day itsuki being cold to him. Like why pushing like that but not confront him? why he choose to avoid him instead? He know yuusei struggling with his feeling yet he keep pushing it. Like yuusei denied his feeling because he think itsuki will never accepted him, since itsuki already ever has a girlfriend before you know. Itsuki know all of this yet he still want yuusei to confess to him with his own mouth when he know yuusei struggling so much
I love the story and keep rereading it but seriously i keep wondering why itsuki didn't just confront yuusei when he kiss him or talking to him the next day? But he actually kinda avoid him even when they going to school. I don't understand he always know yuusei feeling toward him, he want yuusei to tell him yet when he kiss him he doing that. If yuusei actually never talk to him again because he never get the courage and instead running away when they go in university, then everything would be in vain. Like i'm glad they talked but why waiting so long for yuusei to have courage instead itsuki just talk to him the day yuusei kiss him