Thats def not what is going on
They broke up so yeah I think that was the case
I'm not sure if I'm just missing something since the manga was made in 2017 but in the afterword he says that Michelle and him are still dating and are even pondering marriage??
Nope, an interview was made January of the following year (2018) and they'd broken up by then (can link if anyone needs it but it's in japanese). Now whether they got back together or not, I couldn't find out... but Kaoru's pretty active on Twitter if you know any japanese so
But why would that have to do with any of it? As I understand, Kaoru had zero problems with Michelle taking hormones. He writes that he'd been worried about health issues, sure... but he nevers "gets in the way of her transition". In fact, he seems to cry from relief when he finds out Michelle could starts taking hormones again (after being too busy to do so)
Not cool.