Earlier quoted context omitted.
There is more divorce now because it is no longer a burdensome shame to break from a joyless marriage. People change and mature in different ways, and young people aren't known for making sensible decisions affecting the rest of their life. In ye olde days, people would stay with abusive (or boring) spouses purely because the social stigma of leaving was worse. These days that stigma is largely gone in much of the We…
What you say is true, but the grandparent is arguing why people want a divorce and why today's marriages are boring for participants. The implication is that even if access to divorce had been as easy 100 years ago as it is now, people would still divorce less frequently than they do now, because of the extended family stuff.
Human physiology is weird.
Only in recent history have we married for love and in some cultures you don't marry for love. Previously marriage was more like a business arrangement between families. They were also more final because of things like coverture men generally owned all the property of his wife. The woman tended to lose their own identity and become an extension of their husband's identity. My grandma exclusively refereed to herself as "Mrs. HusandFirstName HusbandLastName." For example "Mrs. John Smith." She was never her own name after marriage. My mom said at the DMV they would specifically say on forms "women use own first name."
This sounds crazy but humans have the ability to manufacture happiness.
Since the partners in the relationships of yesteryear didn't have much of a choice in the matter they subconsciously were happier because they didn't have an easy way out nor did they make the choice. They couldn't decide otherwise so their brains manufactured happiness with the situation they were in. This isn't really "fake" happiness, it is real, there is nothing different about it. It is how the human brain works. There is nothing bad about this. It is kinda like a psychological immune system.
If divorce is easy and socially acceptable and you choose your partner from millions of potential partners your subconscious thinks "maybe someone else can make me happier" and you are less happy with your choice.
Our brains "make" happiness with the life we have if we can't choose an alternative.
Daniel Gilbert has a great book on this aspect of humans ability to alter their own happiness - "Stumbling on Happiness"
Here is his TED talk on the matter which has a lot of the same material as the book - http://www.ted.com/talks/dan_gilbert_asks_why_are_we_happy
The following is from my memory and might not be 100%:
For example - he cites a study in which students in a photo class were asked to choose and submit one of the photos to get blown up and framed. One group of students were told that the photo they choose was final and they couldn't change it and the other group was told they had two weeks time to change their minds and submit another one. When the students received their final photos the group who couldn't change their photo were more happy with the photo they choose than the students who had the two week option of changing their photo.
Another one is asking people to rank several Monet paintings on how much they like them. Then they got one to take home. When the researchers came back and asked them to rank the paintings again they ranked the one they owned higher. They like the painting more because they owned it.