The guy knows his stuff - he slowly and methodically fucks her in the anus! And he doesn't care how swollen her labia are and how she caresses them with her fingers. I think the woman just needed a penis in her vagina, or alternatively double penetration with the phaloimitra. And who said the woman even reached orgasm? I only saw the guy come down her anus and that's it!
It takes momentum to make a relationship work. So a young girl brings a fresh breeze to their family relationship. Or rather, a wet pussy, ready to experiment. And it helped everyone.