[2021] CK III - Grandkids will not automaticly get betrothered or married

How widespread is this issue? Is it only concerning landed characters, or unlanded characters as well? What is the scale of the problem, if you could estimate it for us?

E.g. observe if landed characters marry within 10 years of being unmarried or if after 10 years they still remain unmarried?  

Hmm, does it happen for many years? How it's currently setup is that:

1. Around 16 years they can get married if there's a good match.
2. Around 21 they will more actively looking for a match.
3. After 10 years of being unmarried, landed characters will find themselves a spouse.

Can you confirm that this is the behavior, the checkbox notwithstanding? Or do characters (especially landed ones or with claims) end their lives lonely?