Step Child

I have been involved in my step daughters life for 5.5 years . She is going to be 11 soon . I treat her as my own , we bake , I buy her gifts , help her with school work typical things i do for my daughter . In the beginning she seemed to adore me , loved the idea she kinda had a step sister . Recently I’d say over the past 5 months she doesn’t respond to my texts , no more hugs good night just “ good night “ and she is posting on her tick tock how she is a only child . I’m feeling some type of way . Mainly hurt and confused . I asked her why she doesn’t consider ( my daughter ) don’t wanna use names .. as a sister figure all I got was IDK . I said well she thinks of you like a sister ...

I have been told from a friend that my step daughters mother hates it when she referres to my daughter as her sister .... IDK what to do just hurts , and she won’t talk . I expressed my concerns to my BF and he said he has noticed a change to but how do we approach this ...