This is strictly practical advice.
If you have loved ones, make a will.
There are forms online. But really, you should get an estate attorney to help you. It will cost some money. Pay it. It will be worth it.
Figure out if you live in a
community property state or not. These things matter if one person in a relationship dies. You should know your rights now, while you're happy and alive and together so you can make reasonable decisions.
Life is simpler if you have joint bank accounts. You may not want to for all sorts of reasons and that's fine. I'm just telling you, it's a lot easier. If you don't want to have a joint account, make sure that the money is going to go where you want it to go.
Organize your files so you both know where everything is. Life insurance, wills, bills, taxes, SSN numbers, etc. I know it can be pain. I'm not an organized person by nature. Just do it for each other.
We all have electronic accounts, more than we realize: computer passwords, email passwords, blogs, FB, twitter, flickr, google+ and who knows what else. Do your survivors a favor and write down your accounts with their passwords and either give them to the aforementioned lawyer to keep, or put them in a file or safe deposit box; somewhere you both know about.
It may be weeks before the survivor can access any assets belonging to the deceased depending on circumstances. I am fortunate that I have always been the primary breadwinner between us, and that we followed some of the above advice. Otherwise, things could be financially stressful as well as emotionally harsh.
My husband Mark was the sun and the moon and most of the stars to me. Breathing -- surviving -- knowing he isn't here and isn't going to be here is hard enough without having to deal with additional financial worries. We were not not as badly prepared as we could have been, but we were not as well prepared as we should have been.
You can do better, and I urge you, for the people you love, to do so.