So my DD is 15 and not 16 until summer. She has a lovely boyfriend in her year at school (and also 15 until summer). He is a good friend to her and supportive. We like him and his family likes her. All good.
But when he visits ours, my DD takes him into our front lounge and shuts the door on the rest of us. They lie on the sofa and watch TV together, full length cuddling. Me, my DH and our other DD feel distinctly unwelcome in the lounge, to the point that I will go upstairs to watch TV in my bedroom and that my DH will take younger DD out of the house.
BUT: This is our home, so we have all started to make a point of going in there from time to time and sitting and chatting to them, but they never make an attempt to sit up and they both stay lying down on the sofa together. I find this awkward and weird.
We have a second sitting room that we designed for this eventuality when we had the extension for our house (figured DDs would bring boys home one day and didn't want them to go to their bedrooms to hang out, so created a private space downstairs for them). They don't want to go in there as the sofa isn't as comfortable in their opinion.
Furthermore when she goes to his, they lie on and in his bed and chill for hours.
On the one hand I think they need some alone time together. But on the other, I think why do they need to lie on the sofa, spooning in front of us, monopolizing the family room and also, that it's a bit disrespectful?