My boyfriend's sister rejected my FB friend request. I'm worried this means she doesn't like me for her brother. Should I ask my boyfriend about it?

Anonymous
I feel really silly and childish asking this question at my age, but bear with me please.

My boyfriend and I are going on 6 months. I've met his sisters, whose opinions about the girls he's with matter a lot to him. They're very protective of him, especially after his last girlfriend broke his heart. They're awesome girls, and I really like them, and my boyfriend has said that they told him they like me, too. I really want his family to like me. Thing is, when I sent them an FB friend request, one of them rejected my request (the younger one accepted). I'm thinking that it could be because we're not close yet, but I'm also worried that maybe secretly, she doesn't like me. My relationship is great, and my boyfriend is awesome and so much better than the guys I've been with in the past. So I want this to work out. Should I bring this up with my bf? I don't want it to seem like I'm telling on his sister, or I'm throwing a tantrum, but I genuinely want to know.
My boyfriend's sister rejected my FB friend request. I'm worried this means she doesn't like me for her brother. Should I ask my boyfriend about it?
2 Opinion