The "lesbian" couple next door

You leave the house and, after just a short walk, arrive at a driveway with two BMWs parked on it - a pink 3-series and a black 5-series. That's the house of Valerie and Ellie, both of them in their late twenties. You knock on the door, but there is no answer. You hear, however, moaning from the inside and decide to proceed.