How long have you been a single mum? Did she witness the period when you separated?
I’m just wondering if she is wishing you and her father were together, not separated, perhaps because some of her friends’ parents remain together. So she is angry and blaming you (for reasons that you somehow need to glean from her).
6 is a challenging age, when they develop in lots of ways – feelings, thoughts, friendships, etc. We had many development issues with our 6 year old son. Now he’s 7, he has mellowed a bit.
Another thought: do you give her enough time to chill out and be self sufficient? This helps them to be a little more independent, not expectant of entertainment.
Hope helpful.