I began to dislike it. Seme probably isn't a virgin (maybe even he's a fuckboy) and he knows that Inhwi only pretends to know a lot about sex and relationships. So Jongwon manipulated Inhwi into having sex with him. I could possibly understand that he is lying to him in order to get closer to him, to befriend him, to make Inhwi fall in love with him. But what he is after, above all, is sex. He takes advantage of his naivety and innocence. And I bet the author will come up with something to justify Jongwon's behavior, e.g. Jongwon has been in love with Inhwi for years, great love, blah blah, sad childhood and other nonsense
Poor baby