It's where the gf is a fighting coach and the bf can't satisfy her so he wanter her gf to try swapping for one time, I forgot the name
Edit: i think the gf was being trained, the one who was training the gf was a bbc.
Edit 2: first the gf did because it was the fetish of his bf, but later on she enjoyed sex with bbc and kinda like break up on her bf and let bbc pound raw