Going against the grain here, but I think he is just being honest.
Sadly, I think society does revile women (under 60,) who have grey hair, but not men who do.
And I think your DH, if he is also only in his early 40s, does not want to have a grey haired wife. Not while you are both still quite young-ish.
@KindleAndCake it's up to you how you deal with this. As a load of posters have said, it is your hair, but your DH is entitled to his opinion. DH has always said he never wants me to have my hair cut short, as he prefers it long (or shoulder length at least.)
Fortunately, I LOATHE my hair short, and have always kept it with length. If I wanted it short, and I thought it suited me, I would have it short, but he would reserve the right to say he hates it. As I reserve the right to say I hate beards. He had one for about 6 months, and I loathed it. Couldn't kiss him, and hated the feel of it, and the look of it, etc etc. He shaved it off. (As I said, after 6 months.)
Weirdly, on mumsnet, when a woman comes on and says she loathes beards, and hates her husband's beard etc; multiple dozens of posters come on here and back her up, and say she should not have to tolerate it, that she should refuse to kiss him, that she should withdraw sex etc etc...
But when a man wants his wife to not have grey hair, he is lambasted, and she has a 'DH problem,' not a grey hair problem!
Typical mumsnet double-standards.
And please don't say 'hmmm, it's almost as if there are different posters on different threads on different days' because that's a copout. The comments on here smack of terrible double standards when you see the threads about men with beards!
Again, going against the grain here, but I really don't like to see women under 50 with grey hair. I just don't. I think it is very ageing. And that's my opinion.