My girlfriend's friend is sleeping in our bed and I'm not okay with it because they have sex right next to me

My girlfriend brought her best friend to live at our house, and I\'m not thrilled about sharing a bed with him. I\'ve overheard them getting naughty, but I\'m trying to keep cool. One day, my girlfriend catches me listening and gets annoyed. She tells me to stop spying on them and focus on her.