When I was in an abusive relationship, we didn't fight or manipulate each other all the time. I don't think people understand that cycles of abuse aren't always predictable. We'd have long periods of time when we'd act like any other young romantic couple. Then I'd tease her about something and she'd take it much more seriously than intended. She say something even more cutting, and the fight would be on.
I realize now our relationship had way too much psychological abuse, but we were too much alike to see it at the time. We both had to be right, and we both had to have the last word when it came to our relationship. The situation was toxic, and I'm sure everyone around us noticed the cycle of abuse.