Okay, yeah, that's a good twist -- it wasn't a misunderstanding, it was a friend who wanted to spoil a friend.
Also TBH -- I don't actually get a huge trans vibe with this manga. I know my stereotype on MD is inserting trans reads into everything, but I'm not sure I get it here. Yeah, there's definitely gender euphoria and exploration of the forbidden but I don't get the sense of the protagonist being dissatisfied with what they have.
(of course, not that a trans read isn't valid, this is all purely subjective just that I tend to want a few more boxes ticked. I think it's left ambiguous on purpose for the audience to interpret.)
Anyways, this best friend is a total bro and I hate that he's fictional because I'd totally want to have a beer with him.