In my neck of the woods it would be either 1.5 or 2.5. I'd lean toward 1.5 if it were here. 2.5s typically are wider or taller. Most are just outside the ears or close. There are some that are inside, but they have tall racks. In order to field assess a deer a 3.5, I would want to have at least a 2.5 antler configuration but with more mass and substantial brow tines.
By the way, CONGRATS! to your girlfriend!