Yu moves only slightly so that Yosuke can do whatever he wants to. His lips make Yu's skin tingle wherever they touch, and that nip has him sucking in breath, getting him now excited -he was excited before, but this just spurred it on even more.
His fingers wander down to the edge of Yosuke's pants and stop, wondering if it will be okay to go further. He seems really into it and so is Yu himself, but last thing he wants is to have Yosuke do something he doesn't like.