Well it was the wrong present for one of them that's for sure, but definitely the right present for one of the three girls.
@Leonhardt676
It's all the work hours, stress, and forced socializing. Combine that with the high cost of living and you get a population for whom dating/relationships or worse yet affording kids are often out-of-reach while they're still young than in other places.
The culture didn't have trouble back when everyone had their marriages preset by their families, but the freedom that came with the elimination of that system also came with requirements the way of life had increasing difficulty handling as the economy sped up the last couple of decades. It's a problem we see in Europe and NA as well, just to a lesser degree *for now*. People don't have time, are too tired, have already had their fill of talking-to and seeing people for the week somewhere around Tuesday, and may not really have the money to spend on others anyways.
So as far as that teacher is concerned, the available dating pool barring a particularly lucky encounter with all the stars aligning, is... other teachers at her school, if any are available.
Unless she goes the Yokoshima route and starts hunting for students.