I don't like how close my boyfriend and sister are.

My boyfriend is the same age as me, 19, and my sister is 25. I love the fact that my family love and accepts my boyfriend and accept the fact we plan to stay together and get married one day.. But it's annoying how close him and my sister are. I have an apartment with my sister and she is single. My boyfriend is planning on moving in with is in the summer. The thing that annoys me is stuff like she's always texting his phone asking him to do stuff for her. My boyfriend is a nice guy and will do anything anyone ask of him just because that's how he is so he doesn't quite get while I'm upset.  And any time I won't do something for her she says "I'll just ask Kameron to do it he likes me😊" I don't have a problem with my BF helping out at all. But it's like.. Can you not text MY boyfriend all the time and ask him to do personal stuff for you? Maybe I'm overreacting but it's just annoying. Am I in the wrong here?