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.