My boyfriend of one year has finally moved in with my 3 kids and I, 2 of which are mine, a 9 year old girl and 12 year old boy, and another 12 year old girl that I have been caring for for over 3 years. He worked out of state so we spent the first part of our relationship long distance only seeing each other about once a month. During this time my bf and 12 yr old foster daughter grew close corresponding over social media as she lacks a father figure in her life and they bonded over comics. Now that he has moved in I get an uncomfortable feeling when we are all in a room together because they are always messaging and sending pics to each other and looking back and forth at each other. He has never did anything out of the way because I would always read their messages and they are never alone together, but they have been messaging a lot on snapchat also and I can't read those messages since they disappear. He recently told me he was molested as a child and how much stuff like that disgusts him but now i worry that maybe that experience has left him not knowing proper boundaries. I hope he is just showing her extra attention and support because she lacks a father figure in her life, but he treats her much differently than my other 2 children. He has no problem being fatherly to the other 2 but struggles being authorative toward the 12 year old girl. It is odd to me how he stops what he is doing everytime she walks in the room and gives her his full attention. He is always asking about her when she goes to visit her grandparents and always checking her social media. He also seems overly concerned when she doesn't respond to him on social media and worries he did something to make her mad.. I have talked to him about the need to be less of her friend and more of a parental figure like he does the other 2 children, but should I worry about something more inappropriate going on with his intentions? He is a great guy and loves kids and I have no reason to believe it aside from the uncomfortable nagging feeling I keep getting. Am I just being overprotective of her? Or should I be concerned with their extra close relationship?