So you're focusing a lot about the wedding and mourning that -- my question would be what steps is he willing to take sans marriage to make sure you both are protected and looked after legally?

Without marriage you won't be next of kin (and visa versa) meaning

You might not be able to visit each other in the hospital

You won't be able to find out medical information by default

You won't be able to make any medical decisions

You won't inherit his belongs upon his death

You won't be the default beneficiary of life insurance, retirement accounts, or any other financial accounts

Depending on how you set up other financial decisions one of you may be put at a disadvantage that wouldn't be rectified through a divorce if you break up. This would most easily happen if you decide to have kids together, but could happen otherwise.

And a whole lot of other stuff the a marriage license easily grants you that you'd be without. That you would need a lot of documents in order to cover.