I have a friend who is also my neighbour I've known her for 2 years and both have DDs that are the same age. We're both single parents but over he last year I have met my now DP.
We're quite open with each other and chat a lot and let the DDs play together. She recently started online dating because she knew it would be difficult to meet anyone in RL. I completely support her if that's what she wanted offered to babysit her DD and do nursery runs ect if she ever needed me too.
Recently she started speaking to a guy online, they've never spoke before so after a week she agreed to meet him and they did she seemed really happy after and it was great to see her so cheery with a smile on her face.she told me she wanted to see him again but would be difficult with her DD I said I'd babysit and she was happy.
2 days after there first date she decided to invite him round her house with her DD there, he stayed over and has been there for the last 5 days with her and her DD. Over the last two days I've heard him shouting and swearing at her DD and now she does the same. This morning I heard him shouting and swearing at the DDS and she was crying then 5 minutes later him telling her DD he loves her and she wouldn't say it back after my friend was prompting her she lost her temper and shouted "say I fucking love you too now"
I feel so bad for my friends little girl having this strange man come into her life when my friend doesn't really no him and to have a strange man shouting and swearing at her 
Is there anything I can do to help her? She's a beautiful little girl and I'm worried for her