I disagree but only because I don't view Kanon that negatively.
I feel like a lot of people will disagree but personally I just see Kanon as another victim who needs help. She is not some villain who's trying to destroy Izumi and I think people give her way too much unwarranted flack.
Every interaction she's had with Izumi so far, at least to me, indicates she genuinely cares for him. She's simply not equipped with all the tools necessary to break him free from his pain, because she too was never given an out for her pain (hence she turned to self harm and drugs).
Like the drugs chapter. Was it wrong for her to give him drugs? Yeah. But from her perspective she is trying to do something for him that helped her cope. She did it out of kindness, not malice.
And now this chapter. Kanon never tried to pull Izumi away from Kade or the rest of his friend, and in fact seemed genuinely surprised he had friends, something she doesn't. I wouldn't be surprised if this made her feel genuinely guilty for what she did to him.
That's why I personally believe they can both be happy. They're ill equipped to deal with their trauma but that's something that can be worked on. They both love each other genuinely so they can always learn to have a more self-supporting healthy relationship rather than a self-destructive one. A break up is not the only solution here imo.
If she turns full on psycho later I'll eat my words but so far imo she is still salvageable.