I think it's hard for Tsukushi to figure things out because they've just been so close for nearly their whole lives. So, what's really intimate for someone else is just normal in their friendship. But mainly she has the worst case scenario in her mind (being rejected AND losing her best friend) and that's what's holding her back. I'm glad Hinoka is being so patient with her. I think she has a pretty good feeling about what's happening here, so maybe she's waiting for Tsukushi to be emotionally ready and come to her?
Also Sara and Yuu are so frickin' cute. I love that they're confirmed dating.