I’m thinking along the lines of older spouse dies, younger spouse marries someone younger and becomes the older spouse. Then older spouse dies again and repeat. Has anything like this happened in a long enough chain to be significant? Is it so mundane no one cares?
Not at all an answer to your question, but a very semi-related tangent.
The last receipt of a US Civil War pension passed away relatively recently. She was a young woman who would regularly help out a local older man, a civil war vet with no kids or family otherwise. Towards the end of his days, he married her so she’d get the benefits of his pension, as things were really really tough.
Some of the detail might be off, going off of memory, but that’s the general gist.
EDIT:
So I went to double check, and I got a fair bit of it wrong.
Irene Triplett
She was actually the daughter of the woman I thought I was talking about. Her mother married her father at ages 29 and 78 respectively, and she was born one of five children in 1930, living until the age of 90 before passing in 2020.
It sounds like you’re thinking of Helen Viola Jackson. I didn’t know that, but it was at the bottom of your Wikipedia link :)