She indeed is a pain
Personally I think that she didn't really wanted him to hate her because the close relationship between families, would be a pain having to keep seeing him and feeling bad for how she treated him
With the stuff of she not wanting to be in the bad with MC because of the big bro, i can see it, but at the same time I feel that she is not completely interested in him, i feel is a half-hearted interest in her childhood friend, idk.