Disclaimer: I don't own Revolution and never will. No copyright infringement intended.
Miles Matheson feels guilty about a lot of things. One of those things is being in love with his brother's widow. Rachel's a fighter even though she was beaten down for years by Bass, and that's what attracts him to her. He tries not to think about the fact that they essentially kidnapped her because that makes the guilt worsen.
He understands now why Ben fell in love with Rachel. She's a good person and actually likes him. Now he knows where Charlie gets it from and finds he doesn't mind it on her.
Miles really hates himself for this.