William lived in France (mostly Paris) between 1912 and 1917
What was his occupation and do you have any addresses for him in Paris or other proof he was there in the mentioned years? Possible he was elsewhere in France or elsewhere in Europe entirely, especially during the war.
It is also possible that transcription of the letter is incorrect and the woman was e.g. fiancee not wife.
Hi there, all these things are definite possibilities. Unfortunately everything I "know" from that time is so vague. He never EVER talked about his childhood, and I wonder if he lied about the year of his birth also, as his daughters are adamant he was born in 1896, but really it was 1895. His "wife" is, I suspect, to remain a mystery.