Initial posting removed.
I can see 2 (or 3) births for the proposed marriage, and have found a tree on Ancestry with the family in more detail, but with those 2 children and mother private, so probably alive.
Both children appear to marry in this country.
The tree does not know when Joseph Walter died, so perhaps he did go abroad without them?
Also, just realised you are the tree owner - would have been useful if you had put the probable marriage etc.
Perhaps he just changed his name and did a runner?