To clarify-
There are a lot of rights afforded to those who are legally married not afforded to those who can not claim the same legal status.

It appears not everyone is aware of that, so clarifying for those who are not.
This can involve children, property and estate rights, medical decisions and access, rights to spousal health care, end of life decision making, access to a hospitalized loved one, financial rights and how disputes are settled.

The list goes on and on.
Even when same sex couples explicitly and legally give, for example, power of attorney to each other, it can be overturned and ignored and is frequently.

Unless it is a legally recognized status, it can pretty much be disregarded in any situation. This actually happens more easily in emergency situations- where it is most imperative that the love of your life, the person you CHOOSE to involve in your most pertinent decisions, actually be given access.

I don't wish to speak for the OP, as I don't face the exact issues that they do.
I do have people I care about very deeply who have faced the exact situation I describe above and it was terribly heartbreaking.