It was asked of me:
"Why is it that people a few generations ago were ready to marry and start families at 18 (or even younger) while today we have 40 year olds who aren't ready? A lot of it goes back to the fact that our kids are being entertained to death. Everything is play, play, play, and they are never taught to grow up. That in itself has a huge impact on modern "dating". Let's face it, if a person is in the process of dating for 20 years without searching for a spouse, this person is going to eventually do things he shouldn't be doing."
I'm of the opinion that one new variable is that we now live in a world where education (or at least the gaining of a college degree) is more important than before. Accordingly, there are additional pressures that can delay marriage. Having said that, I believe that the main reason for what you have observed is that people do not take sexual sin as seriously today as in years gone by. Accordingly, we have men who keep going to the well of 1 John 1:9 rather than using God's provision for the flesh, which is of course marriage. In other words, if more men would make it an absolute priority to rid themselves of their improper thought life and premarital relations through God's means of appointment, then I think the result would be earlier marriages. Finally, I also find that men can be way too selective. Sure, a man must be attracted to his spouse but so many women are not seen as attractive as they actually are because today more men are lusting after the super models that are on parade. I suppose that many women are guilty of the same sort of thing. {At the risk of taking away from what I have said above, it must be said that there are many single men who are disciplined with their thought life and are earnestly seeking a spouse though getting up in years.}