I think you are presuming too much here that may or may not necessarily apply to me. Since I use my real name here, I am not willing to divulge all the reasons on an anonymous BB which can be easily accessed by patients or licensing boards.
Nonetheless, I took time off for many reasons, but not the least of which was the death of a close family member.
My program director had to document that I took time off for the reasons that I said I did, but no other documentation was required beyond that (ie, no proof of death, physician note, etc.).
Unrelated but amusing given the discussion:
one of the hospitals I am applying to for privileges wants me to document the time gap between medical school and starting residency. If you are off for more than 3 months, they require it.
No big deal, I simply wrote that I moved home, laid on my parent's couch and sponged off them for a few months (since in Oz we finish in January). The hospital wanted a letter of verification from someone who could prove verify that's what I was doing. I wrote back, "do you want to have my Mum call you and tell you I was a lazy bugger lying about her house, because she's the only one that could 'prove' it?!"
At any rate, when you take time off during residency, or more than 90 days off between med school and residency or residency and practice (which I also did), you have to document it and provide a source verification of your statement. It just generally needs to be someone who will sign a form that says, "yeah that's what they did." For you, it depends on how much you wish to divulge but the state of Arizona did not ask for more than the above.