A guy convinces his girlfriend to have a threesome with another girl, however, during sex she seems to be more enthralled by sex with the new girl than with him. He gets jealous and decides to fuck her extra hard to make up for it.

I figure we could work out who controls which two parties, or if there are two people who want to play this (I'd like to be one of the girls), a genuinely three-way thread?

no preferences on canons or mediums.