Why do you feel the need to get married? Especially now after 15 years?
I can’t suggest one way or the other for the OP, but I suggested that we get married, after ten years together, (no kids), because, particularly as I’m 19 years her senior, it came home to me that it would make life easier for her if I shuffled off this mortal coil, and we were legally married
When my mother died unexpectedly, she had virtually shirt buttons in her bank account, but as her next of kin, I was entitled to it, but I had to jump through hoops to get around £800, I had to furnish her death certificate, my birth certificate, and her marriage certificate to my dad, thank Christ they didn’t ask for her marriage certificate for her second marriage, though why would they?
I can only imagine the aggravation involved in going to my bank, and saying, “I lived with Jean-François Blank for X years, he’d want me to have what’s in his account.”
Even though she is named in my will, I’m guessing that it would be smoother sailing if the will said, “I leave whatever to my wife”, and she can then supply a marriage certificate.