A thought: Yugi being mistaken for an elementary school student more than once when he was in high school really had to do a number on his self-esteem/self-image, yeah?
So, consider: Yugi, in his first relationship, especially after his first time with them, being a little overwhelmed because someone actually wants him sexually and sees him as his actual fucking age.
These drawings (and their process vids) are featured in my Off the Cuff series over on YouTube!! I had a blast revisiting this absolutely fantastic arc, and cannot wait to continue on rereading the series from start to finish.