Gog, why shouldn't id theft claims be enforced against a spouse or, as is more usual, a former spouse? They're accepted between parent and child, between those in a relationship etc etc.
The easy answer, to me, is require Prosper to enforce its guarantee then seek repayment from BOTH spouses, to the extent that what the law is. We lenders lend based solely on the data of the ID theft victim, and sometimes based on a description. Prosper then takes whatever steps IT takes to verify the identity of the borrower. If that effort fails, why should lenders be stuck with the consequences? Since Prosper determines what is enough to protect our money, when it is wrong, it should honor its guarantee.
The flip side, of course, is that the guarantee is unconditional. Prosper easily could have said that it would honor ID theft guarantees only upon prosecution, or civil judgment, or whatever other conditions it wanted to impose. Right now, that guarantee SHOULD be worded as something Prosper honors only if lenders discovery ID theft and make a big enough stink about it that someone at Prosper deems it prudent to repurchase.