You have a few choices to consider.
You can choose the domestic partner life insurance policy. It does not matter whether you are a gay or straight couple. They will not deny you coverage under most circumstances. The best part about this option is you might have a reduced insurance rate because of it.
There are no federal guidelines for this option. They leave this to the states to decide, including Washington.
You do have to meet some requirements. You need to be living in the state for at least 6 months to a year, sometimes more. You also need to prove that you have no intention of leaving the state for any reason in the foreseeable future. You also need to show proof that you are sharing the living expenses, including rent and household bills.
You also need to be recognized in the state as a couple who is together. This requirement has some negotiation. You do not need to be married, as you are not, but you do need to file paperwork showing that you are living together, gay or straight.
You also have the option of acquiring a home owner's insurance in your names(jointly). it might not be the same as the life insurance you were hoping for, but it does show your names attached in a joint capacity. You will need to discuss the details with a representative of the company you choose.
You can also acquire something called renter's insurance. It does protect you against most damage and liability. The actual details you have to discuss with the company. It is a way to share a joint partnership under insurance guidelines and remain protected.
One final option is an employer-based healthcare option. You and your partner might already have some coverage. There is always an alternative to traditional insurance options.