Specifically, removing any notion of fault from the termination.

I feel there is a bunch of anchoring going on here.

Why do you think the termination of the relationship naturally has an actionable fault of one party that is being removed?

By the way, do you feel that this fault has to be sexual? Can this actionable fault be ill temper, or snoring, or flatulence, or lack of humor, or insufficient performance in bed, or earning not enough money?

I would like people to be able to credibly commit as to their future behaviour if they so wish.

I don't think so. Putting on a wedding ring looks like a credible commitment to me. What you want is to punish people for breaking their commitments and so far I haven't seen a good reason to do so in the context of marriages.