Scenario poll: source of tiny's "shrinkage" (Patreon)

I'm working on a story with two recurring characters: a man who shrinks and changes size seemingly at random, and his dummy thicc goth girlfriend. I had planned a simple explanation for HOW he got so small in the first place, and why his size changes, but I realized I had no idea if anyone else cared or had opinions on the matter.

So: do you care about the reasoning behind what makes a tiny person tiny?