Why I write both healthy and toxic relationships in my romance stories?

Short answer. Because that is life and realistic. I write romance and mysteries but I want to have little bit more realism into my stories. Also I don't romanticize toxic relationships or abuse. I like to show difference what should be goals in a relationship and what should never be even considered as relationship goals. Long answer...

Writing a character you hate

I'm not a type of writer who loves all my characters. I will never be like that. There are several characters I have created and I hate them. Seriously I hate them. Which does make torturing them fun. I like make those characters suffer and being somewhat punished what they have done for my favorite characters.