Origin of schatzi
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
"German girlfriend," from German Schatzi, diminutive of Schatz, a term of endearment for a woman, literally "treasure," from Proto-Germanic *skatta- (cf. Dutch schat "treasure," Gothic skatts "piece of money, money"), originally "cattle."
Online Etymology Dictionary, © 2010 Douglas Harper