^
My thoughts exactly. This post will merely expand on what Pagey already wrote.
If we walk away from people more easily today than we used to (which I'm not sure I agree with, but let's say it's so for the sake of argument), then I think it's only because we get together more easily than we used to. That's just my opinion.
Relationships--whether arranged or voluntary--have always had an element of the shopping list about them:
*How much does the other person make?
*Are they ambitious?
*Strong?
*Who do they know?
*Talented in or out of bed?
*Humorous?
*Good for displaying to friends and family?
It's much easier to subdivide potential prospects in this age of enhanced physical mobility, with its inescapable and increasingly sophisticated social media platforms. Finding someone who was into yoga, for instance, once relied on a combination of luck and hanging out with the right people (whether these were friends to begin with, or members of a local yoga club). If you want someone who's into yoga nowadays, any social media site (dating or otherwise) can connect you to tens of thousands of people unified in this one aspect (though some dishonestly). If you never thought humans were cheap before, it's hard to function in today's society without accepting it; in the vein of the yoga argument, I read an article recently by a man who was once so into the serial online dating scene that he said he started seeing patterns instead of people, since these people were so predictable (and he admitted that he himself was also predictable, as he kept relating the same inane stories to an endless stream of booty calls). It was that feeling of dissolution into pointless slots that ultimately made him quit, or at least back off a bit.
Five hundred channels, dozens of flavors of ice cream, a thousand places you can eat a hamburger or buy the same shirt or model of a car, and a million people whose connection to you is as tenuous as a re-tweet, FB "like", or a shared love of "Rocky Horror Picture Show". If disposability and interchangeability are possible, humans will aspire to it, because life and attention spans are short, and day-to-day interaction is something like what editors call the "slush pile".
This isn't to say lasting love is not possible, but it will always be a lot more difficult (if more rewarding) than easy come, easy go.