Nice to see our discussion turned into a post. Another thing that I realized that could be a big reason for shorter relationships now is divorce. Divorce is so common now, but is a bit of a taboo back in the day. Couples nowadays see divorce as their easy way out. Any inconvenience and they resort to it immediately. Couples back then are so afraid of a broken family, they avoid the stigma, and being talked to behind their backs. If there was a problem, they try to fix it. If they can't they still stick it out with one another.

Of course, old relationships isn't always nice and dandy. There are arranged marriages and those that decided to stick it out that say they were in a loveless marriage. There could still be cheating, and no happiness in the household. In the end, it might all depend on one's luck in finding a partner.