I've used my miles for many people over the years, including girls I wanted to go on vacation with, my ex-girlfriend/wife, friends, friends of friends, and I was a very naughty boy once although it didn't involve AA. Just tonight I booked a flight for a girl who agreed to go to Vegas with me for a few days.

I think my ex-wife, before we were married, was questioned once, but I think it was immigration asking her where she got the ticket. She told them, truthfully, that I had gotten it for her and she had no idea where I had gotten it because I took care of that stuff. It was one of these things where immigration called me and once our stories matched up they let her pass. (It was in Canada where they have pre-clearance so you go through immigration and customs before boarding to fly to the USA.)

I'd think somewhat naively that AA has at least a moderately sophisticated model that flags likely fraud situations, and a one-off isn't going to trigger it. I mean, yes you could be the one time in 100,000 that something trips you up or someone has a fight with their spouse and decides to take it out on you or your researcher, but it's really not something to stress over. At all.