My understanding of common British nicknames is that names ending in “Arry” are referred to as “azza”, so Harry becomes Hazza, Barry becomes Bazza, Garry is Gazza, so on and so forth. My husband is British so i’ve heard numerous folks over the years with the above names referred to by the same nicknamafication. Harry is likely referred amongst his mates as Hazza, so the nick would have preceded the GFs. That being said, I’ve no doubt that MM took to a British-ism so fast, the phony that she is.