Seniors, why do some spouses pass away soon after their mate dies?

Heart-broken

It could be because of a broken heart and a lack of will to live on alone but, often, it happens just because both were old and frail anyway and would have passed closely together regardless of other things.

It looks similar to a well batting pair in Cricket. After one player is out something happens in partners mind to throw his wicket next.

Loneliness and a broken heart most likely. It will depend on how close they really were to each other and how much of their retirement they spent doing things together.

Quite common sadly. If a couple have been together for many years they simply cannot imagine life without them and literally pine away from sadness and lonliness.

People who understand life and love some, like people used to do. Understand to a degree at least, and especially after living with their sweetheart for many years, that it takes two to make a whole. So when their sweetheart dies, part of them dies too.

I think it's natural in old-age. Depression and shock weaken the immune system, nutrition declines, each new infection is harder to fight than the last. Having younger grandchildren can and does help the remaining grandparent hang on because they still feel needed.

one is a lonely number.

Yes it is proven that a broken heart can cause death when a spouse dies, you can watch the movie Notebook for example. Some may die a few days after or weeks after.

https://www.youtube.com/watch?v=9NSUFdfcqy0

my grandmother passed away six months after her husband died. she was immediately diagnosed with cancer by a lump under her arm but i'm a firm believer in health always being affected adversely by distressing events and trauma. i think her emotions and reduction in will to live affected her immune system allowing the growth to take hold.