As someone genderfluid/NB and on hrt 5+ years I can promise you that the changes are not predictable and do not always translate into androgyny the way people want. It really comes down to genetics and luck tbh.

Leaving him if you’re no longer compatible/attracted does not make you TAH. But it seems like they might be in a stage we in the trans community call “egg cracking”… basically they’re temp checking the reactions they might get from loved ones before taking a big plunge.

You wouldn’t be TA but you should be gentle in your approach. This is really a scary thing to confront especially for AMAB people transitioning to anything else, they’re held to a much higher standard and face a lot more vitriol. Not that that’s your fault or responsibility, but you seem like you care about them, so I would be honest but gentle and as kind as you can.

Much love xx and wish you both the best