I don’t think it is so far fetched of an idea.
A 21-22 yo man can be redt to a 24-5 yo woman. No big deal there. They can still have as many children as hashem blesses them with, she likely has had a job for a few years and can handle responsibility and hopefully at that age he isn’t too immature. And they can grow together.
If the situation allows for the wife to by a SAHM then Kol Hakovod. That is the ideal. Realty though is without help that is high unlikely.