After MUCH searching, I turned up a 1902 version by Roy L. Burtch with the title "Why I Love You." You can find it here: http://purl.dlib.indiana.edu/iudl//isl/sheetmusic/printable/isl-abi-2443-01 The lyrics of the refrain are standard, although the melody is slightly different from the version I learned as a child. The claim of 1945 by Parish, Edwards and Spaeth is clearly false, although it definitely took on many characteristics of a folk song and they did modify it. The harmonies I learned are clearly pre-1945 and with strong barbershop elements.