What strikes me most about your story, off the top of my head, is how much the four of you treat sex as a commodity to give or get, or a bargaining chip -- instead of an intimate expression of your desire and feelings for each other.
Is there any love, caring, tenderness, affection, or friendship among any of you? I get no sense of that at all in what you wrote. Do any of you love each other, or is this just a group of people rooming together and focused on getting sex from the others whenever you can? It seems so sad to me.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein