Does my roommate have a crush on my bf or is she just making friends with him?

I live with my bestfriend twin sister. My bestie got stationed 9 hours away. So i moved in with her sister. We are growing together, becoming friends. Because we felt just like family we love and care about each other but didnt really make the effort for a friendship. If that makes sense. Well, she never got close to my boyfriend. Now that im living with her. He comes over and she acts like shes known him just as long as shes known me. Picking off his Plate, asking him to fix things in the house. Fyi im handy and have done all the fixing in the house so far. But she always askes him to fix or do something when he comes over. I love him and trust him. He doesnt do anything she askes. Unless i ask him to or tell him to. But idk how to approach her about how i feel without ruining anything btw me and her.