My niece is 11, nearly 12 and has a "boyfriend". Her parents seem to encourage this by allowing him over for "date night" where they watch movies in her room. They refer to it as date night. They've been allowed to go to the cinema alone, eat out alone (Mcdonalds..) etc.
Someone else I know allows their 14 year old's girlfriend to stay the night (separate rooms)
Surely this is too young?