I will never believe that Katherine lead Damon on, when she admitted it herself that she also loved him. I think she changed him for a reason. She stated that when she was giving him a goodbye.

Why do you see Datherine as a toxic relationship? I don't see it as a toxic relationship. Their personalities match with each other. Their ego are the most important to them, they are both evil, they try to be good but end up failing, their chemistry, they both tend to be self destructive, and I love their characters best with each other.

In my mind, they are together in hell