I ask my fiance outright if he'd like me to wear/do something. When we first met-up (we started dating before we met in person) if he'd like me to wear anything special or put on make-up for him. He said to come as I'd feel comfortable. So I did. I wore a nice t-shirt and a pair of jeans and no make-up. I learned very early on that he appreciated nice underwear, a well-fitting dress or pair of jeans and when I'd wear something he got me. I also learned that he wasn't bothered about make-up, messy hair (or bad hair days), extent of shaving, painted nails..etc
Yet the women who put the most effort into their dress are the ones who have JUST started dating a man who they think is a catch. [Note: the sort of woman who takes pride in being a home-breaker puts the most effort into her dress when starting to approach a married man. But they're strange outliers, nowhere near the norm.] They may have known him for 10+ years. He's seen them in silly pajamas, without make-up, on a bad hair day or with unshaven legs. He knows they can be like that. But they're worried they don't look "appropriate" or that other women will hit on him/"steal" him. It extends to weight, too. Teenage girls with EDs often want to be skinny because (due to their obvious lack of confidence) other women "flirt" with their partners right in front of them. They think being thinner will make them look "right" and protect their relationship, when a bit of obvious jealousy, a serious conversation with the partner and a confident act in public would do the trick better.
Other women can be very, very strange.