These may be one of the reasons:
1) she doesn't want to lose u as a substitute in case the guy
she likes really reject her one day.
2) she only treat u as a normal friend and doesn't wish to let u
think that u are not good enough for her, so she kept praising
u.
So, either way, she doesn't like u. Move on dude, unless u are
willing to wait for her. 
Not to wait is good
