Because every person will die at some point, it would seem like being prepared would be manageable,...but this is just one of those things we simply can not totally prepare for.
My spouse of 14 years was diagnosed with cancer, and 10 months later gone. You would think 10 months would be a good amount of time to prepare, it is not. Rather than being prepared for the loss, I feel strongly that you should be enjoying the time they have remaining; which will better serve you when the end does arrive.
In terms of monetary preparedness, you should work together toward making certain you have considered your partners well being for when you have passed, a plainly written will and life insurance policy are the kindest ways to show just how much you truly care about your loved ones. You might think this sounds trite, but soothing the immense anxiety surrounding the new things that the people left behind must contend with (funeral, paying bills, medical expensive accrued and so much more) is a gift never to be forgotten.
Nothing can change you or your life as much as the loss of a loved one. My biggest piece of advice is to always choose love in everything you do together; for our mortality is immanent.