Well this was one hell of a surprise break up.
This is the end of our union is not being accepted, even though when we point to "związku" the word "union" is suggested.
Yeah, it's possible, but mind what would be the meaning. Could be: związek zawodowy (a trade union), związek sportowy eg. związek koszykówki (Basketball Association, lit. union of basketball).
Well, związek is not only a relationship but also (and foremost) a union, an association. Group of people bounded together, having a common goal.