Well this is new. What woman doesn’t want to go on a date? Seriously red flags for me. Unless you have a birthday she’s secretly planning something big, or yeah that’s all I got, what would prevent her from going? Is she suffering from depression? I know I talk about it a lot but that’s because people are truly suffering in silence.
As a boyfriend I would have to ask follow up questions. Just a simple cancellation isn’t enough to come to a conclusion. She also could be under a deadline for work in which case you would have known that ahead of time. I would ask her when she was available and that you want to spend time with her and miss her.
Long ago are the days when men are out making things happen. Women are out making it happen too. It could be a balance issue. If she hasn’t figured out how to make all the turning wheels spin at the same time then she just needs to be reminded you are here as a support system.
My next question is where is your relationship? I hate to be the heavy but what was your interest before hand. I’ve had many times dated men who were emotionally unavailable and after many times of asking for time etc I simply moved on. I on one hand was up front but some women feel like the writing is on the wall and just move on. I’m not saying I condone the behavior I’m just offering perspective. Whatever is going on a conversation is definitely necessary. Men have feelings and she still needs to be mindful of yours but you have to be willing to speak up. Good luck keep me updated!