Of all the romance tropes that exist, it's the older-guy, twenty-something gal that's the most irritating, and it ties directly to this trope here. Men get old, women get replaced.
It's almost as if all women are worth is how good they look. This is evidenced in all the post-makeover shots where the camera lovingly pans up the beautified girl in question from the tips of her toes... but doesn't always make it all the way to her face.
I call it "Pervy Cam" and have failed to find any reference to it anywhere. It also includes shots from the rear that linger on the lady's bottom as she walks. But that's a rant for another day.
You see it in game shows. You see it in Talking Heads morning shows. You see it in the freaking NEWS. Male anchors are allowed to age to retirement. Female anchors are not allowed to exist after they pass a well-preserved 40-something. They're more frequently not allowed to exist after 35. And they're definitely not allowed to exist past 5-months pregnant.
Why? Because the media caters to males. Males are the least likely to want to watch/spend their money on things, so the media lures them in with visions of young, "healthy"1, smiling and theoretically available women.
Older women don't look sexy enough. Pregnant women past a certain point don't look sexy enough2. Therefore, they're shunted off to the side and neatly excised from our screens.
This might be why films like Mad Max: Fury Road and Wonder Woman were so groundbreaking. They had a refreshing lack of this trope. Themiscera featured women of all colours and ALL AGES, being portrayed as EQUALS. Mad Max did the same. With older women turning up and being bad-ass with it towards the third act.
Further, there was no Pervy Cam in Mad Max or Wonder Woman. But that's my next rant.
Usually, if there's an older woman on the screen, she has little character to her other than to be Mom or Grandma and, almost always, die for The Feels.
We get it. Older women aren't sexy enough to be allowed to live. Thanks a bunch for that evaluation of approximately half of the human race.
What we need to do is keep pointing out this shit as no longer acceptable and demand at least an equal age peak for men and women on TV. Meatier roles for the ladies should be happening too. We can do these things. It's just that we too frequently don't.