Some scenes are level specific to each individual character. Meaning if you go into the bathroom at the same time of day with a character at level 1, then did the same thing with the character now at level 2 or 3. You would get a different scene. so before you improve the characters relationship level your need to try get all level specific scenes. If you dont, the only way to get them is to start a new file and try every action with a character until you find the missing scenes.
Also in this case, the last scenes are ones you can only obtain with all skills maxed out. So check to see if your fingers, tongue and banana skills are maxed out.