Chapter from Bridget Jones

I sometimes feel as though I'm living a chapter from Bridget Jones's Diary (book or movie version, doesn't matter). For some reason, I have an unstoppable ability to be a complete idiot when interacting with a particular someone. When I come up with something clever to say or write, it comes out all jumbled, as though the butterflies in the pit of my stomach have intentionally bumbled the words, playing tricks on me to see how ridiculous they can make me sound. Or worse yet, nothing comes out at all. It seems it's been this way since day one of meeting him.

Is there some sort of chemical reaction or magnetic friction that causes this phenomenon?