> I'd expect tears from our visitor and a high likelihood of violent resistence if you try to send them back.

I'm not so sure. See the antropologist https://en.wikipedia.org/wiki/Kenneth_Good_(anthropologist) He married a native girl named Yarima, but after several years in Western society she choose to return to her tribe in the rain forest. Life as a Medieval peasant seem to me to be inferior to life in a hunter gatherer tribe, but I think it is far from certain that the peasant would refuse to go back.