[Thess]

Going to send the Rider answers in a PM, because they contain spoilers?

Originally Posted by SJCrew

Also, I'm very baffled as to why you guys feel the need to defend Kariya when you're basically restating what I said. "He's insane because of the worms." Uh...yeah? "I endured all of that for you and Sakrua" isn't the clearest indicator he doesn't recognize the woman he loves. "I'll never forgive you if you deny all that?" Clear and conscious [?] rebuke...of the very same Aoi he loves. With the horror on his face as she enters the church to Tokiomi's...who could he have possibly mistaken her for? Lmao.

But yeah, the jealousy, rage, and worms and stuff drive him to attempt murder.

Spoiler:

And curiously enough, we discover mid-Episode 25 that Aoi somehow ends up surviving to become a basket case and cripple for the rest of her life. Not sure what the point of that was.

chaos_alfa already gave you the novel quote. Kariya's strain wasn't only emotional, his organs (including his brain) weren't functioning. Look at this description of him in the initial battle (episode 5) to see how the anime tone down his suffering (the manga portrays it very well):

Spoiler for novel:

Trying for a long time to stabilize his breathing, Kariya collapsed on his back on the freezing asphalt.

Blood covered his body. Most of his capillaries have exploded. Blood slowly flowed non-stop from the cracked parts of his skin.

A long time ago, Kariya once saw the victim of a nuclear power plant explosion struggle against disease. Right now, his appearance and situation was no different than the victim prior to his death. His body of flesh has already been destroyed. But there are Crest Worms spread across Kariya’s body. Its magecraft extended his lifespan and allowed him to wiggle.

That was in season one.

Of course jealousy and other factors played a role, but the man wasn't in a state to sip tea calmly. He was practically a zombie.