I know you identified these, but, I am going to run down the list:
1. Tax benefits.
2. Ownership/probate. In most states, if you die intestate, the "life partner" gets nothing. If you die with a will, the bequeathing in the will is still subject to challenge by blood relatives. If married, those issues go away. Also, most states are "marital property" states. So, you get joint ownership of all each other's assets (and debts.).
3. Financial transactions. It is much easier to get a home mortgage, auto loan, etc. when you are married and both on the account. Especially when a home mortgage, it is a lot more difficult if you are not legally married.
4. Medical and end-of-life decisions. A spouse is the default decision-maker. Otherwise, the "life partner" has no rights to make decisions. Even if you have a power-of-attorney or a living will, blood relatives have standing to challenge your decisions.
5. Health insurance. Nearly every health insurance plan has a family or "plus one" option for a spouse. Very few allow "life partners" to join the plan.
6. Social security benefits, IRA, pension, other retirement accounts. Surviving spouse gets benefits.
7. Leave benefits under the FMLA. You get up to 12 weeks leave to care for a spouse (or other family member). Does not apply if not married.
If there are no dogs in Heaven, then when I die I want to go where they went. - Will Rogers Emery's Third Coast Triathlon | Tri Wisconsin Triathlon Team | Push Endurance | GLWR