Get the pre-nup...
Been married for 14 years, no plans to divorce.
But in that time, there have been a couple of close calls. Over the years, there are events which can stress even the best marriage. One stressor event might not be enough to kill a marriage, but they can and do add up.
Some events simply can't be predicted, especially events outside the marriage that are completely uncontrollable. What if some relative needed to live with you or die on the streets? What if one of you gets injured in a car accident to the point of altering that person's personality?
Or events inside the marriage that are completely uncontrollable. We've got some close friends who's 2nd child died in the womb at 8 months, their 6th miscarriage...*that* really taxed their marriage to the limit. What if one of you finds (or loses) Jesus/Mohammad/Bhudda/etc in a big way and the other doesn't? What if your sex drive increases with age and your spouse's decreases (or vice versa)?
And so on. And so on...the stresses on a marriage are as infinite and non-stop.
As a side note, my wife and myself actually have a pre-nup, mainly to protect her assets. However, over the years, we've co-mingled things enough such that our pre-nup is pretty nullified at this point. Plus, my earnings from stock options in the 90's ended up exceeding her expected inheritance anyways. But I fully understood why she wanted a pre-nup and felt no ego bruising when signing it. It made perfect sense.
Anyone who gets upset over a pre-nup is (a) selfish and (b) living a fantasty world...and I personally would want to marry someone (a) unselfish and (b) living in the real world, where things sometimes go wrong no matter how perfect a couple you are.
...Dave