Your husband is surely feeling insecure. I don't know how old you both are, but you've been married 16 years, so you're not teenagers by any means.
If you haven't really been in the habit of taking extra care of your appearance, it may seem odd to him. But, it doesn't have to equal red flags either.
Men think differently than women. That's a given. I personally tend to think that women get better as they get older. You get your kids raised, you start wanting to put some focus back on yourself and thinking about your own needs for a change. It doesn't have to be the same thing as thinking less about your husband.
I've been a single mom for a long time and juggling two kids and a job, I got to where I never wore makeup unless I was conducting a meeting or something. Then, when I had to go on disability for a while, I just threw on anything comfortable and clean for my physical therapy appointments, etc. I didn't care. But, I realized that I'd been slacking when my son came home from school one day, and I actually had makeup on, and he said, "Mom! You look really pretty....where are we going?"
We weren't going anywhere.
And you know it's bad when even the mail lady says, "Wow, you look really nice today."
I don't think men understand that getting gussied up once in a while really is something that we just do for ourselves. When you look good, you feel good.
At least your husband notices! I gave my friend an awesome new haircut because she wanted to surprise her husband and he didn't even notice. I cut 8 inches off her hair and it looked so good! He didn't even notice until she finally handed him the ponytail that I had cut off.
Men!
I think what you should do is find a couple of women's magazines that have make up tricks and hair ideas and articles about how to look your best at 30, 40, 50, 60......
New hairstyles, new clothing styles, new trends in nail polishes and makeup. Many mags have makeover tips. Find some that have articles about looking your best for your man, how to keep your marriage sizzling, stuff like that. Have him look at them with you when you're laying in bed watching TV.
It might help him to see that it's a "woman" thing....it's about feeling pretty and looking pretty and feeling confident. If he says he doesn't "need" you doing any of that, say thank you, but YOU need it for yourself. Other women get their nails done, other women wear makeup, other women get new haircuts. It's a woman thing. It's not just you. Wearing makeup and dresses to work doesn't mean you're not happy in your marriage.
My sister has been married 15 years and gets every new hair style, different colors, the newest glasses, manicures and pedicures and her husband always tells her how sexy she looks. He's not worried about her going anywhere and she's not a priss. She'll throw on a flannel shirt and sweatpants with no makeup and her hair pinned up to go camping, fishing or clamming, rototilling the garden....she's not a slave to beauty, by any means. But she does like fixing herself up.
One thing I like to splurge on when I can, is pretty bras and panties. Even if no one but me sees them, I feel pretty wearing them.
You might want to invest in some with your husband knowing he's the only one to ever see them. One of my male friends buys his wife pretty things from Victoria's Secret every year for her birthday without fail.
Try some of these things.
If your husband is truly afraid that doing things for yourself signals trouble in your marriage, you might need to go to counselling to help him get over that. He may be worried that you are coming into your own and beginning to flourish and to him, that means he might get left in the dust.
What does he do to make himself feel like he's evolving? Does he have hobbies? Does he tend to be afraid of change in general?
Depending on the level of his insecurity, anything you do could be seen as a threat to him or his comfort level, but that doesn't mean you have to supress yourself or your happiness.
I hope you get some good responses and I hope that he will come to see things from your perspective a bit.
Rent "Jeff Foxworthy: Totally Committed".
It's funny, and he talks about the differences in how men and women think.
I highly recommend it and it might give you a chance to open communication with your husband.
I wish you the best.