Well in a way, the other guy is a piece of crap too. Granted his head is screwed on more tightly than Kae's, but he's the one who's been attempting to rip their relationship apart in the first place. Wanna know why the entire fanbase wants Kae's head on a spike? The other guy. He was the one who was pressuring her (and knew how she reacted to Mirage Saga) to go and everything else in between. If it weren't for him pushing her over the edge, she probably would have left on time to see Mutsumi.
Also, he's kind of a jerk. Just saying. Two-faced, manipulative, not the best guy to hang with but not the worst.
Now I blame Kae on this too. If she had even a quarter of a brain she'd know that a con is of less importance than Mutsumi. Also, this whole this with the manga attempting to put other people to blame other than Kae is getting on my damn nerves because 75% of this is her fault. But the other 25% of the fault goes to the other guy.
Honestly, at this point, I don't really care who sempai ends up with anymore [hoping he's/she's not as screwed as Serenuma]. I just want him and Serenuma to break. I'm just glad that the glasses guy appeared to stir up Serenuma's feelings. Maybe she'll learn because of this.
Honestly? Shit with Serenuma, hate me all you want for this, but she's getting on my nerves. I'd be happy if Senpai will end up with the other guy instead. Yeah. Make it yaoi.