when is it ok to sleep in the same room as bf when 12 yr old is around...

i lived with my boyfriend for several months and stayed in the guest room b/c i was uncomfortable sleeping with him when my son was with us. his dad and i try to raise him to wait until marriage, or in love and older, etc....traditional view.a year and a half ago his dad got engaged, moved her in and slept in same bed. my son was very upset. we may move back in with bf, we've been together 3 years. he is almost 13 and knows about the birds and bees.is it ok or is it hyppocritical to stay in the same br with bf?