boyfriend and his parents

My boyfriend is 18 in 3 months. He got home at 7:30 tonight (it's a Wednesday ) because he stayed back and did homework at school then got good with me. His parents didn't bother to message him but they took his phone off him and he isn't allowed to use the computer or internet. Don't you think this is unfair? He's almost 18 and being treated like a little child. Also I don't think his parents (especially mum) like me. She's always rude and he stayed at mine and they wanted him home so early and he wasn't home in time so she messaged me saying she's not letting him waste his year 12 schooling. (It was a Saturday and he did all his work) I feel like they blame everyhing on me 
What do i do?