I first read the question and it was an absolute deal breaker.... and then I remembered, DH wears “women’s” running leggings at the gym - he likes the fact they’re brightly coloured and he says blokes running leggings are always boring black. I also had a boyfriend who wore makeup (eyeliner and lippy) in the 90s.
I think the difference is, for DH now and that boyfriend then, they aren’t/weren’t “dressing as a woman”, they were dressing as themselves, as a man, though not according to stereotypes.
It would deal break for me if DH cross-dressed and described his motivation as wanting to “dress like a woman” or if it was sexually motivated. But if his motivation were more along the lines of, “I’m a man, I like these clothes, men should be able to wear these clothes whilst still being men” and it wasn’t a kink, then it wouldn’t.
I think this is how I feel too. Clothing is just clothing, and wearing something because you like the cut/colour/fabric, etc wouldn't bother me. Wearing clothing aimed at women as a kink is not the same thing.
And actually, DD recently had a boyfriend who wore some women's trousers because he felt the cut and colour was better than some mens trousers. I honestly couldn't tell they were women's trousers, he simply looked comfortably dressed.
And now that I've been thinking about this, I recall my mum telling me she'd bought some girls clothing for DBro as a baby and toddler because it was more colourful than the boring dull blues and browns common in the 1970s.