I think it was when the seme forced himself on the uke
But it doesn't look force at all tho. It looks like uke gave concent to seme and all but dunno Σ( ￣□￣||)
i think the uke was awkward about it. and didn't know how to take it. or like always some high school rumors that made him nervous. or he is scared of the change cause they were both guys and in high school. having sex for the first is off putting. and with our uke being a sexually person he probably liked it to much it scared him.
In the recent chapter or in the back story part? He doesn't seem to have a good reputation with consent cuz he kissed that guy when he was asleep.
To me it looked like the seme was into the uke, and expressed that physically by kissing and touching him without asking. Stuff like this is pretty common in yaoi.
I smell trouble #－.－)
And seriously what happened in the past that made things awkward?
P.s i was jungshookt by the 1st chapter. That scene tho ヾ(☆▽☆)