I don't want to hijack the OP's thread AllThingsServeTheBeam and that I don't think all men who have long hair are cross dressers, is so obvious that it shouldn't even need to be said.
I don't even necessarily think it's the case here but what the OP says in several places ring enough alarm bells to make me suggest it as a possibility, which is something that I don't do lightly.
It's the dynamic of the very sudden change in behaviour, the imperviousness to how it is effecting the people close to him, and the slightly distasteful ( to the OP) levels of preening that make me mention it as they're signs I recognise. It also feels like there's some secrecy about his motivation.
As you have asked, these are the things the OP has said which could be red flags for cross dressing based on my years of experience of this:
I have tried to discuss it and he said if they werent bullied about this then it would be something else and that wouldnt make him change his hairstyle. There appears to be no compromise.
He just gets defensive
it takes such a long time to wash each day
I can only think mid life crisis
Do you think he wants me to issue an ultimatum so he can get a divorce
it does sometimes make me wonder if he is having a hidden breakdown or wants a new life.
couple of times when someone has seen the long hair at a glimpse and presumed female
he is pulling it out of the way all day
has several conditions and then detangling brush from what i see. seems a long time to me compared to my hairwashes.
is not able to say why the change
constantly tucking it behind his ears