What marriage benefits do you wish weren't confined to marriage?

[roboticanary]

Something I think should be put to the forum is to ask what benefits currently given to couples would you want to be more extended outside of marriage/civ partnership where you are:

A few of my ideas (UK):

If you are unmarried and have a joint mortgage, you don't necessarily inherit the other person's share if they die. even if you live together in the house that you are mortgaging together. 

There is also a small marriage allowance, basically you can transfer money to a higher earning spouse  from your allowance (the amount you earn before you pay income tax) giving you an effective tax break. 

spouses recieving state pension income (If you are single in the UK your pension ends when you die, but if you are married your widow can live on your pension). Really wish I could pass this to, say, my younger brother. I understand it is not a good idea to let me pass it on to anyone far younger than me but it would be really nice if there was a bit more flexibility than just spouse.

[Nagito]

To have permission by signature on a simple document to receive information about health of other person.

[roboticanary]

Oh that's a good one.

I would like to add a better way to allow visitation rights as well.

I should be able to specify beforehand with my medical records people who can visit me if I am seriously ill rather than just spouse and some close family. 

Interesting that all this stuff would be really useful for unmarried couples as well as non romantic relationships.