Mears, My mum let my boyfriend live with us when I was 16 years old. By 17 he was sleeping with me.
I can understand why she did it, and I loved her dearly, I but it was IMO a wrong decisions on so many levels and affected me for years afterwards.
I met BF when I was 15. I was enjoying a nice teenage social life, a few boyfriends but nothing serious. He didn't get on with his father and came from a large family who where living in overcrowded conditions. My mother took him in out of kindness and because she really liked him ( I was an only child).
But, her kindness meant our relationship got more serious that it should and I was trapped. A relationship that should have petered out just kept going.
BF was possessive (so was my mum in her way). I totally - and I mean totally - missed out on all the sixth form parties, friendships, clubs, and group fun etc - I was shy to begin with but my unusual set up at home made me feel so out of kilter with everyone in my class, that I stopped mixing, I couldn't invite people back home or slip off to see them. People got so curious once they found out that I avoided saying anything. I began to not go to school and just scraped through my A levels. Then nearly didn't go to uni, as it meant leaving my BF at home with my mum and I felt I would be usurped. I ended up studying for a degree at our local polytechnic, while living at home with BF and mum. It took till I was 21 to ask BF to go, even though I had fallen out of love with him years ago. I just felt I couldn't deprive my mum and him of each other.
I left for London, and spent years feeling socially out of my depth with men, as I had missed so much when I was a teenager. I also could not settle in a steady relationship and made some unwise decisions over boyfriends.
I met my husband when I was 28, but could not comtemplate having a child with him, even 3 years into marriage and mortgage, because a bit of me was still so afraid to get tied down. He managed to persuade me to try for a baby when I was 34, and I am so thankful he did.
I am not blaming my boyfriend living with me for everything, but it did have an effect on me for years afterwards.
I know you are discussing sleeping together at home, not living together, but I think even that can be dangerous if condoned by the parents. It can make if really difficult for a girl (or boy) to back out of a dead end relationship. Having the excuse that 'my parents won't allow....' can be really useful and it can give you some distance between your BF just when you really need it. It was such a mistake for me to have had a steady relationship from the age of 15 - 21. I will do everything I can to avoid my sons doing this.