Haimy is making a good point. The choke points in shidduchim are the shadchan and the boy’s mother. the shadchan wants the easy shidduchim because she needs to make a living. The mother wants a fantastic shidduch so she can feel worth-while and successful and have bragging rights with her family and friends.
As far as the math, say there are 100 boys and 100 girls in each age group, and the boys begin shidduchim at 23, and the girls at 19. So: age 23 – there are 100 boys who are looking at a pool of girls 19-23. That’s five years worth of girls, at 5 x 100 = 500. But the numbers never even out, because as the boys age they keep looking for girls who are younger. so inevitably there are going to be girls that never get matched. From what I’ve seen, a lot of the older unmarried boys are unmarried because they’ve gone off the derech but are keeping it quiet because they don’t want to hurt their families, particularly the younger siblings’ shidduch opportunities.
So what’s going to happen to those “left-over” girls as they get older and realize they’re never going to make a match in the frum community, and will never have the chance at marrige and children? Some of them will marry non-religious Jews. And probably some of them as they approach 40 will give up and marry non-Jews. Our next crisis may be a couple of decades down the line when we’re trying to figure out what to do about a group of young people who are halachically Jewish but whose fathers are non-Jews.
I suggest we get working on possible solutions fast, unless we just decide that those older “girls” and their potential children are expendable, so kol Yisroel areivem zeh l’zeh is irrelevant. I wonder what the One Above would think of that kind of attitude? I’d rather not find out.