She doesn't even look healthy anymore

There are many reasons why she is aging so quickly.

1.) Long-term analysis of her behavior, talk of her from close eyewitnesses, and things she has done, indicate that she is very unhappy with her body as well as her genetic heritage. She not only dislikes her figure, but she has made attempts to change it, such as when she wore breast enhancements while on "Deal or No Deal," and she's been known to wear butt prosthetics to give her tush some definition. She is a plastic surgery addict, having changed her nose shape several times, most notably in high school to erase the African American flatness, as well as enhancing her cheekbones to give her face a more "white" look. She's been known to even use the kind of plastic surgery that involves polishing the skin to remove wrinkles, and the skin can only take so much abrasion treatments before it can't handle it anymore.

2.) Meghan loves using all sorts of beauty treatments on her face and hair, but up-close photos show that she hasn't really been taking good care of her skin (it looks really pebbly up close), and spends a lot of time outdoors in the sun. Daily exposure to the sun with tanning can age the skin prematurely, which is a common problem for women in Southern California in particular. Her hair is probably also suffering from years of straightening treatments. She naturally has fuzzy, nappy, curly African American hair, but has had what some call the "Brazilian Blowout" treatment done to make it hang straight and behave like white women's hair. Treatment like that can be very harsh on hair in general, particularly after a decade or two, and she's briefly shown signs of it falling out, or having to have extensions put on, or even wearing wig pieces that are very well-matched to her real hair to enhance her appearance. She probably has also been dyeing any gray hairs that have been growing in to look black like the rest of her hair. You don't reach 40 without at least one or two stray gray hairs showing, and she obviously hates that she is aging now.

3.) Meghan is a drug addict. She loves to smoke marijuana as well as tobacco, she does coke, and probably indulges in other drugs we don't know about. She doesn't drink as much as Harry, but she most certainly enjoys getting drunk at parties. All that indulging in drugs and alcohol can have a detrimental effect on your appearance. Like the sun, smoking for a long time can age the skin prematurely, and excess usage of cocaine can sometimes lead to nasal collapse, bringing about the need for a plastic surgeon to rebuild the nose if the collapse gets bad.

4.) According to people close to Meghan, she has an extreme aversion to getting fat, and has done everything in the book to keep herself skinny (she only gained weight temporarily for that NYC visit to fake like she had put on "baby weight" after her second fake pregnancy). She's done every diet in the book, including "going vegan" and taking Ozembic, despite the dangers its side-effects pose to the user.

5.) She's been under a lot of stress because her marriage is a sham, and her old tricks of getting ahead aren't working anymore. She can't even trot out her royal pet "Haz" to get people in Hollywood to talk to her anymore, nor will a lot of fashion brands speak to her and let her borrow their stuff now. Too many in the acting and fashion world have gotten to hear what kind of a person she is, and they're frankly sick of her. Even worse, she can't go running off to find a guy stupider and richer than Harry because her reputation precedes her, and she's getting too old to woo such men. They like younger, prettier, better built women than Meg. So she's angry at the world and stuck with a lame-duck prince. Their marriage is so bad that they haven't even been living together for 2 years, but fake being together for the public. She still has him emotionally chained and trapped with her, even at a distance. He's too stupid to realize he could end this at any time, but he still wants to protect "mommy" through his wife, and is willing to put up with the abuse once in a while.