Girl's Behavior

Should I ask her why she didn't say goodbye?

I've known a girl for three college years and it's been on and off throughout these years. Long story short she is very cute but was seeing someone. The only move I made was when I asked for her number and she rejected me then I found out she was seeing someone. Anyway, the next year she started acting flirtatious calling me pretty, and that she misses me, etc. Fast forward we became kinda close friends (though without communication outside of college), but at the same time we flirted a few times here and there. Anyway, throughout these years I have enjoyed her company many times, and now that college was about to end, the final day, I asked her not to leave early cause it's the final day. (I actually just wanted to say goodbye to her). I thought I'm gonna miss her even though it's not right. I kinda expected this, but when I finished the exam, she wasn't there. I didn't tell her goodbye, it kinda made me sad. I know she's seeing someone, but as a friend who has been with her for three years, I at least deserve a goodbye. My question is should I message her asking why she didn't stay or say goodbye? or should I just leave it?
Should I ask her why she didn't say goodbye?
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