He supervises the fucking that they give to his cousin
A man knows that along with him, the people who make up his family nucleus must be protected. They must be happy and content with the things they do. Doing what they want to do is what they deserve and the male of the house must guarantee that they can do it. Right now this guy is doing his job as an alpha when his cousin wants to fuck a stranger. He supervises that they give her a good fuck and make her pussy enjoy since it is their job in the pack. That’s why she is very happy and surely when no one wants to fuck her, she will accept that he fucks her too.