I think someone else explained it before but...
Kou isn't forcing Yuki to do anything, both Kou and Yuki have their own preferences, but Yuki doesn't seem to be overly bothered or embarrassed /to be in/ women's clothing, but he is sometimes bashful in reaction to Kou's requests as a reaction to his affection, not the request itself. Rather he seems very happy when Kou is happy. So I think the thing is...
Sometimes when you like someone, you just want to look good and do little things that make them happy. Kou also always emphasizes that Yuki looks good in anything. If Yuki ever seriously said no, I think he'd accept it. Because to him Yuki is his perfect partner, and he also wants to be perfect towards Yuki.
But yeah anyway it's not like the manga is without problem, that much I agree.
Bro it's the person not the geneder if it's not Yuki he wouldn't like him ╮(￣▽￣)╭
Just like in Thai BL series you kniow
gender*
This is so stupid. Kou says he doesn't like guys, but is in love with Yuki, a man. Yuki wants to cut his hair and wear masculine clothes, but Kou guilts him into looking feminine. He wants Yuki to dress up as a girl, but everytime someone thinks Yuki is a girl, Kou outs him and embarrasses him. The art is really cute, too bad the story is manipulative and gross.