Dean didn’t have the best grasp on normal adult relationships, considering his parents' situation.  His mother was dead, and his dad handled it worse than even Dean could see himself handling the same situation.  But his dad wasn’t a saint.  He went out, screwed around, and still, Dean never ended up with a female role model at all.  Bobby had conversations with him often about how a lot of his issues with showing emotion were from only having a damaged father as someone to look up to, other than himself.

As she explained the complications, his mind wanted to hear them as excuses, causing his eyebrows to stitch together in a bit of rage, worry, and protectiveness.  He didn’t accept that someone could hurt the people they loved, no matter the reasoning.

Dean turned his gaze from Sarah to Mika’s face, trying to find in his mind a time that he would ever hurt her.  He went over several scenarios that were what he considered the worst, and he realized that she would be his weak spot, if she was ever taken, or it came to him being forced to hurt her.

He turned back to Sarah as she spoke about Mika not wanting him to see her when she was bruised or down.  He couldn’t remember a time that he even had a hint that this was going on, other than the one near fight he had been involved in with her father, that Bobby stepped in for.  Bobby seemed really protective of Mika that night, and now Dean knew why. 

“I um…I hope you understand why I can’t let him hurt her again if I’m around.”, he finally muttered, meeting her eyes with a serious and almost possessive look, “I don’t want to hurt your husband.  I trust you, when you say you see good in him.  I do.  But what happened today is on me.  All of it is on me. 
I can’t…let her go through this.  I’d take a bullet, ma’am.”