At what age can he start to spend the night?

Isabelle
At what age do you guys think that a couple can start spending the night together in the same bed? When should parents allow their child and signifigant other to sleep together (and I do mean sleep). I think im too young but in my 18 year old mind he's the one and i wish we were treated as a legitimate couple, not two teens who are just trying to have sex.