We used Irr Differences and we just had to both agree to use it. We then both waived the 2 year rule. Neither of us had to prove anything as this is just the standard "no fault" option.

I could have used drug addiction or alcoholism but then I'd have to show proof. (The rehab invoices and DUI probably would have been good enough but why bother?)

Given how long a divorce can take (mine was 13 months), you'd be surprised at how quickly 2 years flies by.