You have a different idea.

Without warning you lift Frannie off the floor, holding her under her legs as you move to sit onto the couch. You then position her so she was in the reverse cowgirl before lowering her onto your cock.

"Ride me bitch..." You growled into her ear, causing her to gasp as your hands moved her hips, forcing her to move. Frannie braced herself by placing her hands on both your legs before taking over, continuing the pace you set for her. Now that she was moving on her own, your hands move around her body, lightly touching her skin. She moaned at both the touch and the feeling of your cock. Your fingers slowly brush over her still flat tummy, knowing full well what will happen to it in a few months. You then move your hands up to her generous breasts and start caressing them, holding them in place to prevent them from bouncing.

Sarah has recovered from her fucking and quietly slips off the couch and makes her way to the both. Frannie was unaware of her presence before she felt something lick at her clit. She gasped and looked down, seeing Sarah with a grin on her face. "Fair is fair Frannie." She said. "You helped me to get off, now I'm returning the favor." Before Frannie could protest, Sarah resumes her licking. The combination of your hands massaging her breasts, your cock in her pussy and Sarah's licking was too much for the girl, causing her to stiffen up as her orgasm hit her. Sarah smirks before moving her mouth to your balls, taking one of them into her mouth. This was enough to trigger you and you end up cumming inside the other girl.

One hour(and a shower and laundry) later.

Both girls were redressed. They did not expect for their little announcement to break out into a wild fuck session, not that they were complaining. But now that the passion has subsided, there's one thing on the girl's minds. What about your wife and the children you have with her.