The options don't disappear randomly, but depend on how one plays and what actions one does. They are simple variables that increase or decrease according to the interactions and how many times it does or doesn't do it (like when the choices become white, green or red). The games of SNC are full of these choices and you don't go on doing it all once or twice, but many, many, many and often some choices block others (like the anal sex option at Barbara's house). It all depends on how you play.
If you want an example these are all the variables that are controlled to bring to the scene in Melida's bedroom when William is drunk