Mcpendo my 2 cents are that, and in experiecne of other male and females i have heard from is that:
unmarried older girls are also usually prouder somwhat, possibly due to thier maturer mind and likely high education level.
Relative to this, In our culture younger girls are still more preferable for marriage, however inspite of this fact and maybe arising from insecurity issues many older girls still possess in simple terms a bigger-headed mindset.
And also from personal experiecne, the older girls probably are maturer and intelligent likewise they tend to want to dominate/control a younger guy, i.e try to be the boss, as opposed to the guy being the head of the marriage or relatinship.
However this is only my general opinion from my observations.