Enemy isn't worthy to be a protagonist for slapping his "loved" one. Any protagonist wouldn't care if they were to be found out and just beat the crap of his enemy.
Judging from the colored illustration the girls would eventually enter the dungeon, so they will eventually know.
That candle is some high level aphrodisiac both parties gets affected.
He had talent, because of his trauma he couldn't move forward. Now he nows everything, I'm excited how will he be. Not saying it's that easy to be relieved from his trauma.