My kids are young (8 and 5) so I haven't even considered this yet -- but reading this post made me think of the first time I brought home a boy: I just assumed it was OK, but my parents were nervous. We ended up sleeping in the living room "sleepover style" in sleeping bags. It was fun!
Subsequent visits he slept in the fold-out while I slept in my room. We didn't sneak around because we found no need -- when we were at his place we slept in the same bed. There was never any question from his single dad that it was totally fine for us to be in the same bed. Ironically enough, we never had sex - it was just about cuddling together and being together.
For the "coming home from college" trips, the boyfriends always slept on the fold-out and I in my bed. This was true even for the days leading up to my wedding. The night before the wedding, my parents requested that my husband-to-be sleep in a hotel so we'd be separate until the actual wedding. (At that time we had been living together for 18 months so it was purely symbolic.)
