Yukari doesn't need to tell Maki anything.
If Maki really cares about Yukari, if she is really a "friend", then she only need to be there giving emotional support with her presence, nothing more. But maybe Maki doesn't want to be a "friend", she wants to be more to Yukari, and that's why she needs Yukari to tell her what happened.
Now I suspect that Maki is only hanging out with Okuda to use him to do something about Sakura.