Aside from using your preferred pronouns, what does it mean to treat you as your gender?

Sometimes people say "I want to be treated as a man/woman". I'm not sure what that means though, aside from using preferred pronouns.

There is an example I can think of. I used to date a non-binary person. We always went Dutch on dates. Now I'm dating a woman. She does not like to pay for dates, because she's a woman. To me, that seems like sexism.

Is there a way to treat you as your gender in a way that isn't sexist, aside from using your preferred pronouns? Shouldn't we just treat everyone the same regardless of their gender?