I'm kind of against the grain here, in that I think this chapter actually showed that they do make a good couple. I don't understand why Yame started dating him in the first place, but since they've started dating I think they've both grown, Junichi especially. The fact that he's moved past just wanting to lose his virginity and actually realised he likes Yame, and he's turned down the other girls, speaks to his growth, imo. At the start of the series, he probably would have accepted Kashii. (Though maybe not Nene, cause she's like a little sister to him) Also the fact that he wanted to make up with Yame and got her a gift, he's making an effort. There's genuine affection between the two of them, and it's not just Junichi trying to get laid.