The first part:
Even smart people who think they have it together can become involved in a bad boy/bad girl relationship. I used to not understand how someone could get herself involved with someone so obviously unhealthy, or choose to stick around once the situation goes south. But the whole business with Brett came up on me gradually. It wasn't like he was a jerk right out of the gate. When you experience certain things day in, day out, they start to seem normal, no matter how abnormal they are.
I reacted to Brett's little sideways insults with anger at first. He would always tell me I was overreacting and after a while I kinda convinced myself that I was. Same with his drinking. Two 40's on a school night might seem excessive to most people, but I knew that on weekends Brett usually drank three or four and so I was glad that he was toning it down. The person in the bad boy/bad girl relationship may not be viewing their partner through the same filter you are.