They regain control.

Fight or Flight.
Stay here and regain control
or
Run out now and hope she never finds out.

Steve chooses Fight.

He spanks Eve's ass, giving her a simple answer.

"Is that so? We didn't discuss..."
Another spank.
"I mean, it's not my first threesome, but..."
Another spank.
"Well, as long as he's not some stranger, I guess it's..."

Derek shoves his cock back into her mouth.
She makes no objections and resumes sucking his cock as Steve resumes fucking her.

It isn't too long that the latter feels like he's going to cum.
Not wanting to risk knocking up this crazy slut (his thoughts, not mine), he stops himself and pulls out with one last spank.

He signals for Derek to to take his place, who happily obliges.

"Why'd you stop? Oh, it's his turn no-mmph."

Derek begins to pound away at Eve, who sucks Steve dick clean until...

He cums hard in her mouth, filling her up.