My son who is 12 is aware that I periodically check his phone to ensure that he is safe and everything is appropriate. Upon looking at his text messages with his girlfriend they are clearly being physically intimate with each other when he's at her house. There is talk of touching under clothing and digital penetration. When she comes to our house I don't allow him to close the door, however her mum is clearly not keeping an eye on them at her house. I don't know where to start in talking to him, but clearly they are far too young (gf is also 12) to be sexually intimate. Ideally, I don't want the relationship to continue, but I risk upsetting him. Please help 🙏