You heading is very misleading. You started by saying Derek cheated with Addison when in fact it was the other way around. You did not do your homework before writing and you just put a little nugget about Addison cheating. They were separated when he met Meredith and later on fell in love with her. He's McDreamy throughout be it his looks or his dreamy eyes and all his accomplishments as a world-class neurosurgeons. Millions love and adore him, it was MerDer who captured hearts of viewers all over the world. Addison lied by omission. She did not tell the truth about her and Mark living together for months, had a baby and even aborted it after Derek left her.