The chick is used to being treated this way. The impotent husband lost her at cards. That's why they've been pulling her like a bitch all day long. And the harder the stake, the harder they drive it inside. Only the pussy is already so used to the new masters, to the abundance of milk - that she does not want to go back.
The couple had sex with mutual attraction, so there's really something to see here. It's not a tender relationship, but a passionate one. The guy fucked his pretty brunette sister in different positions, twirling her legs and ass in the process. He did not forget about the male pleasure - there was a blowjob, and after sex he cum on his sister's face, on her heated and young skin.