Fiancé /step daughter

So i have been with my fiancé 4 yrs and he popped the question this year in February but come to find out he never told his daughter. But the crazy things his daughter never wanted to bond with him until now she is 17 and only converse with him when she wants something. He have asked her numerous of times to spend time with him she always so no until Yesterday she came over we went shopping she barely spoke to me when I asked her questions and she would leave from beside me when he walked off then come back towards me when he come back it’s like she is using him in my eyes but he so happy to be around her that he don’t see it . On top of that her mom feels that she can call and text him whenever and I feel it’s disrespectful when she already caused so much drama in our life. Am I wrong for feeling some type of way