I do not know any 28+ gals who are single... but I am sure there are plenty now a days....
What's the future likely to be for these girls?
If you don't know them or not seen them then why worry? It is a good thing if you don't know them since there might not be a lot of them or they hang around the single people. So your hubby is safe! :-)
Chances are they are still looking for the right one or their parents. They might have missed the chance earlier too for any reason not their fault though.
By this age, if the right one is found, there should not be a reason to stay single since a woman's fertile age is rather short. We are talking about 28+ here.