Really feel for you & your fiance. I have travelled to the USA at least once a year for the last 10 years with no problems (apart from once getting caught with to many cigarettes ) My eldest son lives & works out there and had to go through the process of obtaining his visa after the initial 18 month one expired. Never realised what a lottery it is. You get accepted from your application which, in the time it takes & the massive numbers involved, can only be from pulling out of a bag. He then had to go through the Embassy experience back here, successfully thank god, but the guy in the next booth was rejected.
Coincidently I have just got an email telling me my ESTA travel authorisation expires in 30 days. The daft thing is you have to apply all over again & not just renew the expiring one Surely having had a record of you it would make sense to offer a renewal process.