Step daughter doesn't like me anymore?☹

So I've been in my step daughter life since she was 5...she is now 7yrs old. She was the sweetest little thing when I met her at 5 also at age 6 she was the sweetest ever. She still is sweet but not as sweet as 5 and 6 lol. Now that she is 7 she is very sassy. Usually when I ask her what she's playing or could I do her hair or if she wanted anything she would reply back to me. Now that she is 7 she just looks at me with a mean face and always says "nooo" or won't say anything at all or will randomly tell me to stop watching her play her game on her tablet. She use to love me watching her at her games. Now it's like NO NO NO lol everything is no and she rolls her eyes at me. So Today were all in the kitchen (me her and her dad) and I ask her if she wanted some juice and she yells NO angrily. So I look at my boyfriend and say (I'm starting to think she doesn't like me anymore) and he goes she does like you. So I walked to the back room to get in the shower. And as i get to the room. I hear her tell her dad ( I do like her) and he says to her (well you're really rude to her so she thinks you don't like her you gotta stop being rude) and she didn't say anything after that. It really just has me thinking...if she truly does not like me idk how I could move forward in a relationship with my boyfriend..when I came back out I rinse the conditioner out my hair in the kitchen sink and she looks at me angrily and says (YOU'RE WET) I started laughing and said yes my hair is wet. Then she runs back to her dad in the living room lol. I literally buy her whatever she wants..I try to play games with her like we use to but she doesn't want me around anymore. She only comes over every other weekend to be with her dad and the other times she's with her mom. I seriously do not know if I could move forward in this relationship if his daughter is going to grow up not liking me. What would you all do in this situation?