My spouse's sidepiece

Spencer comes back saying she forgot something. She hears something suspicious and heads towards the bathroom. Avery makes it up to the bedroom in time to see Avery, seemingly alone, toweling off. Spencer gets horny and starts hooking up with Avery. Avery kneels at the edge of the bed and starts going down on Spencer. We then learn that Scarlett is hiking under the bed. She starts fingering and down on Avery without Spencer realizing. Eventually Scarlett gives herself away and Spencer realizes she is there. She demands to know who Scarlett is and why she is under her bed. Avery thinks fast on her feet and tells Spencer that Scarlett is a girlfriend of her that she convinced to come in for a threesome.