My daughter didn't really like to have sleepovers at all so it didn't even come up until her first boyfriend a few months ago. Since she had already asked me about birth control, I just figured they'd be more comfortable in a house than in the back of a car. I don't think his mom feels the same way but I didn't ask her. I think when she stays at his house, they are theoretically housed in separate rooms but they "stay up" all night in his room or some fiction like that.

My parents made some attempt to house the boyfriend in a separate room from the daughter when my sister first brought a boy home but I guess they gave up on that by the time I brought a boy home.

Edit: My daughter was almost 17 when she started dating. I was 18 when I brought my boyfriend home from college.