What is that Chinese saying?  You will know your best friend better after five minutes than an acquaintance in 10 years...or something like that, and I think it says it all.

I know older, married couples who have been together for upwards of 30, 40, 50 years, and for most of those years, they barely have been able to stand one another.  Part of this is anthropological -- people really did marry in the earlier parts of the 20th c to have children and security and didn't expect much more.

Now our generations (I am an "X") want to marry/partner our best friends.  What an amazing progression...

Imagine healthier and happier humans!?  No matter how many years they've been together.  :)