Sure, adding a year of high school for girls might help the “shidduch crisis”, but it would be completely unfair for parents, teachers, and girls. How would the curriculum be decided? Why should girls stay in school for a thirteenth grade and still get the same diploma as the boys who graduate a year earlier? Why should we unnecessarily make the teachers and students work harder and the parents pay more money?
High school girls do not go out on shidduch dates. Adding a thirteenth grade would delay girls dating for a year. Instead, why don’t we let them graduate after twelfth grade and simply not date for another year? They don’t have to be in high school; they can be in seminary or college or have a job. Whatever they’re doing, they just won’t be dating.
More high school is not a solution.