More people are getting divorced over 'second life virtual adultery'

What the heck is second life virtual adultery? It’s hard to explain. I get very confused trying to even follow the story. But it seems to be that there is this online community called “second life” It involves what I percieve as total craziness, online sex, virtual cheating, avatars, just stuff that makes no sense to my non-technologically advanced brain. Check out this article about a real life British couple who got divorced due to virtual “second life” cheating.
Crazy stuff
What are they talking about?!