Years before it was obvious my sister was a lesbian I was the only family member that knew.
She would use my house (one bedroom flat) to be with her girlfriend.
On occasions I would be in one room while those two were in my bed.
Many of times I found pubic hairs and stains on my sheets, it also smelt nice.
It would have been even better if her girlfriend at the time was nice looking, unfortunately she was very butch looking and a lot older with dreadful tattoos and naff gold jewellery.