Poll: How long does a love relationship remain worth it?

As average, how long time does a love romance survive as happier and objectively more interesting than... the greener grass on the other side of fence?

In other words, how often should one (as average, though varying case by case) change one's partner, in order to live a maximally happy lifetime?

via International Skeptics Forum http://ift.tt/1VNcnux