> I generally agree, but they're focused mostly on 65+ age group

Another aspect possibly driving this: In USA a lot of people get divorced immediately after a cancer (or similar) diagnosis. That way only one of you goes bankrupt and you get to keep half your lifetime savings.

A few trends which might be relevant:

  - First-time parenthood is frequently occurring later in life
  - Couples are more often having (additional) children at later ages
  - Children are sometimes not "launching" until later in their 20s.

So, ~35yo first-time parents and/or ~40yo youngest-child parents, plus ~25-30yo children moving out ... That can get you to 65-70 years pretty easily.

Alternately, it might be that the cohort now age 65+ was more likely to divorce than the previous generation at every age throughout their lives, and there were some kind of generational effects involved.