No one can claim to know who the basherte is. This is subject to a huge discussion of which to be honest is not relevant to alleviating the crisis. However if bas ploni l’ploni means that everyone married their basherte than please explain all the older single girls with no one to match up with. Who is their Ploni?????? He got married to someone!
Isn’t that the ultimate point? To marry your bashert? And does everyone really get married? There will always be a percentage that don’t (some people dont want to, some people cant, some people just dont find the right person) and I wonder if that portion is what you are calling the “age gap difference.” I don’t think 100% of men or women ever got married.
Also, most of the people I know (anecdotal I know) married within 2 years of their age and many married the same age.