To preface this, I'm currently crashing at my mother's 1 bedroom apt while I'm looking to get a new job &amp; move out. So my sister (20's) &amp; her boyfriend(50's) drove in from 5 hours away to visit us for the weekend. My mom offered them her bedroom so they wouldn't spend $$ on a hotel, &amp; her &amp; I would sleep on the couch, no biggie. Meanwhile bad timing, mom ended up sick with bronchitis &amp; not feeling well, I'm taking care of her the whole night. 

They went out all evening &amp; came in after midnight. I was exhausted as last few nights i didn't get much sleep &amp; I also have been feeling ill, so I was tossing &amp; turning, didn't end up falling asleep til after 4 am. While at 3am I hear moaning, &amp; sure enough I had to hear them having sex... in mom's bed... While we're just on the other side of the wall on the couch. 

I'm thinking WTF? They're adults &amp; couldn't wait 1 day to fuck back at home, but instead decided a family audience Next to them was no obstacle? Next morning they shower &amp; eat breakfast with us like nothing happened. After they finally leave, we change the sheets &amp; clean up the place. I brought it up as I was grossed out &amp; apparently mom didn't hear them (she was passed out). She's not as bothered about this as I am, probably bc she didn't have to hear it. 

Am I wrong for feeling they betrayed home boundaries &amp; were just disrespectful for that choice? Am I just being cranky while I'm exhausted &amp; sick? 