Hi Jesper Lee,
Thank you and I am glad that the videos have been helpful to you.
If you truly want to be her platonic friend and understand that she has no interest in you romantically, you can send her a snap.
However, if your only desire to send a snap is because you continue to harbor romantic feelings for her and you are hoping that you will have another chance with her in the future, it may be best not to send her a snap.
In a scenario like that, yes, you should leave her be and accept the rejection.
You may believe that there is something between the both of you and that you were just unable to engage her in the best possible way at the school party.
However, do understand that as human beings, our minds can make us believe some rationale that we have concocted simply because we want a person so badly.
The sad look that you saw in her eyes may have simply been due to her feeling bad about rejecting you as opposed to feeling that it just wasn’t there between the both of you in that moment.
In essence, try to avoid making yourself believe that there was something more. It is best to take what happened at face value and accept it so that you don’t continue hanging on to what would most likely be false hope.