What does a girl mean when she says 'stop being so nice'?

d of a theme going on with my questions lol. By nature I am a gentle caring kinda guy. Met this girl with 4 children, from day one I knew that the girl had been in an awful relationship and her oldest daughter (14) had witnessed more than she should have. I've met the kids and the girl told me her 14 year old really likes me, unlike the former partner. I love kids and treat them all like my own, its the only way I can be. I treat their mother with the respect she has always deserved. However she says stop being so nice, its too much. Any ideas.
Updates
+1 y
When I say too nice.. the 14 year old had no school uniform, and believe me the mum could not afford it... and I wouldn't see any child go without like that. So I took her shopping.
What does a girl mean when she says 'stop being so nice'?
Post Opinion