I think Alex is pretty toxic too, just in a more subtle way. It's mentioned many times how he's constantly looking down on Cole, and Brad even says that he purposefully chooses problematic people as lovers so that he can feel superior, and then takes them for granted. I think that's probably not the only reason he's with Cole but still, it's there. In these chapters he's also incredibly insensitive of his feelings and gets mad the moment Cole isn't agreeing with him, even tho he's the one who asked for his opinion. Also I think we shouldn't forget how Alex almost killed Cole after being provoked by Brad at the office. Just because he's the one who got cheated on it doesn't mean everything he does as a reaction to that is justifiable, he obviously got issues
Okay Ngl but honestly I feel Alex might be the best character in this. I know people are saying Cole and Brad should be together but they both trash. Literal trash since they cheated. Alex was and is faithful throughout this whole Manga and has been trying really hard to make it work with Cole. Meanwhile Cole at every opportunity when something takes a slight turn in their relationship (bad) he either wants to kill Alex, wants to kill himself, or cheat. Cole needs to go to therapy ASAP and start working on his relationship with Alex because boy this relationship cannot float on toxicity forever. At this point we looking at either a break up or someone ends up dead. Cole doesn’t deserve Alex anyways and just go with Brad since they have more things in common.