Dad has recently gotten himself a much younger girlfriend whom he has moved in last month. My bedroom and their bedroom are wall to wall. The fact that they fuck doesn’t make me uncomfortable - so happy for them, but they do it on max volume. No joke. Every night at 11 and in the morning at 6 on the clock. These walls are paper thin apparently.
I’ve been in a similar situation. As another user already said, you should be direct about it. Pick a good time (when they are not doing it) and simply explain that they are loud and ask them to be more quiet.
If you still want to be subtle, maybe try knocking/hitting the wall between your rooms, this will probably be noticed if it’s night, and they could realise that they’re bothering you.
Encourage them to get married. It’ll put an end to that shit tout suite.
Welcome to 1979 where marriage is terrible!
wife bad!