What's the cringiest thing you've done in a relationship?

Never been in a relationship, so I'll share my cringiest "rejection". A girl in my college class probably knew that I liked her because during breaks I'd approach her to talk to her. One day, right as class was about to begin, I told her I would ask her a pretty important question during break. Midway into the class, she left to use the bathroom, or so I thought. She never came back to class that day and never came back to class from then. Thinking back on it all, I think I might have come off as a creep to her because I would look for her a lot during break... but I never wanted her to feel uncomfortable around me if she was :/ It's cringy and I feel horrible about the whole thing.