I cant tell you it will be fine…
What I can tell you is it COULD shorten its service life. It will have to slip the bands more than normal, it will probably cook the fluid faster than normal, and the torque convertor may never lock up due to the effective gear ratio. What does this mean? Depending on how long you keep the jeep, it may mean nothing for you. If the trans has a normal service life of 10 years, you may shorten it to 8 or 9 (just throwing numbers out there to illustrate my point).
I CAN say if you regear, you will be MUCH happier. I just got regeared yesterday after running 35’s on 3.73’s for 6 months. While it was perfectly driveable and I could do a lot of offroading, I couldnt use 6th gear (I have a manual trans) unless I was doing above 75, and any steep hills or big obstacles while offroading required higher than optimal RPM’s.
So can you do it? Yes.
SHOULD you do it? I wouldnt do it on 3.21’s. You will be MUCH happier if you regear.