Lol he seems to just have a bit of a bad disposition. Otherwise he seems fine, especially since you could tell he was a bit worried about Haru's sudden choice to drink
Tbf, the person he's in love with seems to be thinking about her dead friend entirely. Rikuo thinks thats the only reason she's back, and to hear that "dead people matter for to someone than the living" just further cements this in his mind. At least he was able to realize that he's acting out...