Stress out about it

If one thing remains constant from your childhood, it is to keep your promise. That's one of the reasons why you keep going after Sasuke as you promised Sakura that you will.

And now you have screwed up by promising Sakura that you will go out with her on what you consider to be a date, even if she would hee and haw as well as deny it when asked, while at the same time arranged a time with Shizune.

You consider going after Sakura to tell her that you can't make it but you don't think you can stand seeing her disappointed face. On the other hand, you wouldn't want to disappoint Shizune, not when she has given you a mind blowing orgasm not an hour ago and will most probably give you a few more tonight.