It's something that those in the "Shidduch Crisis business" don't tell us.
This!
The Age Gap Theory is nonsense.
Not in the sense that it cannot be true or isn't necessarily something to be concerned about, but in the sense that it's promoters are advocating that it is THE cause based on "mathematics" and shlepping in chashuve Roshei Yeshiva and Rabbonim on that basis.
Their math is all fuzzy handwaving and back of the envelope calculations, and efforts on my part and on the part of others with similar backgrounds in statistics (and actuarial science) to address these issues have been met with condescension, obfuscation, and ridicule.
At this point I refuse to engage with any of their promoters even when asked, it invariably ends with their trying to "explain" to me how I don't understand the math.