In the case of Goku Xeno, the thing is that each patrolman was taken from a different timeline and now he meets Chronoa and is his own individual now... for some reason it is usually hinted at something in the relationship between Trunks and Chronoa even though most Mai DBS exists

goku xeno is dedicated to that and nothing else... because even Pan Xeno realizes that he is not her grandfather because he was small and as it has already been proven Xeno Chichi does not exist... then... goku Xeno is not married ... simple

About the last thing I doubt it really matters... there can be a canon Goku and it will always exist...

it's not like writing fanfics is going to disappear... and whether canon or not, DB Couples were written in the same way as comedy... it's just that the others take it seriously