Hello @Laura1355. It's embarrassing, I know, but we live in the third millennium and I can not stop people from having sex.
What, however, I have to expect from the guests is that if they intend to have sex, the rules of my house must be respected. They are in my house, and my house must be treated with the respect it deserves.
For this reason, in a discreet corner of the bathroom I left a small basket with boxes of condoms, sanitary towels and painty liners and a sign indicating the container where to throw them. Some guests even thanked me for this thought.