Sweet O:) Welcome and thank you for working on this! :)
I played through the demo again, and here's the mentions of his gender I found:
"Jealous? I may have a couple dozen "hazubandos" but I've only got one "booifurendo"."
"Hey, how about you go on the "you already ate and don't get a say in what I have for dinner" diet, Mr. Healthy. I'm hungry for pizza."
"What? It's a thing, Mr. Health nut. I saw a guy do it on the internet. In fact, there's your diet right there. Degrease that sucker."
"Aaaand, you're still carrying an empty backpack and a map… OK dude."
The one I was thinking of was a reply option early on: "It's just a map. A guy can't have a map?" I guess in my head I turned the others into callbacks to that, sorry. (She also refers to Wilson as "guy" once or twice, I probably put him and the mouse dude in the same mental bin.)
I'm not sure about this one, but together with the others it feels like it contributes: "Plus if we were both fat our bellies would smack together when we do it." I could go into details, but… yeah.
Finally, the general stereotype of "you're supposed to like action movies, I'm supposed to like romance movies" seems gender-based… especially since May ends up liking the action movies far more than the romance movies.
(I really do miss her reactions every time I encounter that "no animations" bug <\3)