Hold out (for Kristy's sake)

You politely-break the kiss with Allison, telling her why as you do. You pull out of Trish's pussy as well.

"That was amazing, but I don't want to finish my part just yet," you explain, "Let's try some new positions."
"Well, your tall friend here still owes me for getting me left in this position."
"That's true. I'm up for eating some pussy- especially when it is all wet like this."
"Does that mean that you're going to fuck me," Kristy asks.
"Hell yeah. I know just the position too."

Allison climbs off of the bed and gets down at pussy level to start eating out your tied-up friend. You get Kristy to climb on top of the bound girl and start to kiss her.

You move in behind her and slowly insert your cock into her pussy. She's wet enough from cumming to make it easy.

So now you are fucking the hot brunette while she makes out with her bound roommate that is, in turn, getting eaten out by your naked roommate.

It isn't long before Trish cums again, but Allison doesn't stop.

Kristy is next, being more sensitive than ever after being eaten out by your friend.

As for you, the break helped you hold out longer than you thought possible. Keep thinking about baseball, math- anything!

Both ladies cum once more, but you are at your breaking point yet again...