Honestly, I choose to ignore some signs of flirting because I was a bit too often the butt of the joke of the "did you really think I would be flirting with you" game some of the girls in a few classes were playing. And I apparently was the most gullible guy out of the nerds. So yeah, that is a trust issue.

Doesn't help that most of the times I did try flirting after that, the girl wasn't actually flirting with me.

On that note, why is women flirting always "parade around and let him hit on you" kinda shit? Immediate repellant for me.