Mary Ellen Arnall

[damac]

Kenneth William Mackenzie married Mary Ellen Arnall in Plymouth June 1906. On their wedding Certificate he is named as John William Mackenzie, he remarries in 1923 and his new wedding certificate states he is a widower.
we then assume his wife has died but I cannot find in any searches what happened to his ex wife, anybody know what might of happened to Mary Ellen Mackenzie nee Arnall?

[Milliepede]

The marriage registration index Devonport Jun 1906 gives his name as William John so that's another combination of names 

What name(s) does he have on the second marriage certificate? 
Presume his fathers name is the same on both.

They are together in 1911 with 2 children.  In Cornwall.

[Milliepede]

There's a family tree with mary ellen death 1972 so, if correct, a remarriage for her husband claiming to be a widower wasn't legal (unless they were divorced)

[damac]

My mistake it did say william john knew I would get it wrong, on his second marriage certificate,  that I do have the full one of and not a transcript it is Kenneth William Mackenzie his father was John.
My parents think  that Mary Ellen died my aunt is on the fence as not sure.
I am aware that there is a family tree around with her date of death 1972 mine and on other which have remove the dates from because we cannot find anything on her, I did see her.
I have seen a mary ellen arnall boarding a ship for toronto Canada of simlar age,  just don't if this is her.