I imagine this is similar to the way it was with my Wife and her Huge Ex.
When she gives me handjobs, she always tells me that her hand was much too small get around his thick cock - there was at least one inch between her thumb and her middle finger like here... She likes to show me how thick he was by opening her hand very wide and going up and down around my thin little dick to show me how much bigger he was than I am. And then she shows me how easily she can go around my tiny cock using just her thumb and her pinky. Big turn on!!