This type of MMF meetup is taboo for many people. The man who is fucking the woman is also actively sucking another man’s dick. For a lot of participants and viewers this crosses a psychological line, which some find appealing.
Anal hitting so deep the pussy starts shaking. Pelvic floor locked in, nerves firing, that thick dick making her whole pussy pulse with every stroke. Who else gets their pussy twitching just from getting their ass stretched?