Wasn't the guy supposed to be unpopular? To me, his school life doesn't seem like it. He even has Chiffon to hang out pretty much all his time in school.
On the other hand, it came off the mouth of a girl that might be interested in MC, considering the fact that he appears dense, not recognizing false statement from her.
But really this was probably the first time I disliked MC here how he dished Chiffon in front of the other girl. There are 2 kinds of dense, one in the sense that he might think it's a 'rom-com magic influence' that made her act like that, but something else making accusations she would do it with anyone when she is pretty much hanging all the time with him. Does she even have other friends? It was really low. Even if he sees her as a friend, would that kiss really destroyed everything? He is acting like - oh kiss, how lewd, she must be my girlfriend first for that or something ridiculous... Oh well, romcoms rarely go past that kiss and a few panty shots, unfortunately.