When I was a youngster, the Interstate highways had not yet been built in our area, and most of the roads were narrow, winding, 2 lane "goat trails" that went through small towns, over scenic bridges, and over spectacular (if frightening to some) mountain passes. Then the freeways were built. Although they were bland and ugly, they were safer, easier, and shorter, and most people (including my parents) chose to drive on them exclusively, even though many of the old roads still existed. Fast-forward to my college years when I got a car, and I started to revisit some of those old routes. At first they brought back a lot of fond childhood memories. What I found though, was that as I drove the roads more, those memories began to fade, and the roads and scenery only reminded me of current times. In the same manner I suspect that your wife, upon first seeing you shaved, was reminded of her terrible ordeals with chemotherapy, and was understandably upset. However, maybe (I am not certain, of course) with time, as she sees your shaven head more often, these horrible memories will begin to fade, and eventually bother her no more. There also are therapists who can help desensitize a person from these kinds of negative associations. Just something to think about, and I truly hope that the Mrs. enjoys good health from now on.
