I have seen this as a very common complaint with many girlfriends that I know. Apparently most of the time it's out of jealousy.
But to be fair it's out of societal expectations, guys are nurtured from childhood to work hard forgetting everything else including physical and mental health to provide for others, and girls are encouraged to look pretty and find rich, stable guys.
Parents of girls spend huge amounts of money on a girl's look from early childhood and girls continue to spend a pretty good amount of money on looks afterward too. Plus they can hide flaws behind specifically designed makeup, accessories, clothes, and shoes.
Guys, they have to solely rely on nature. Some guys grow huge muscles but they are actually way harder to maintain and totally unrealistic for many professions that guys are generally into.
So it's very natural that most men will not look good compared to most women.