The arc would have finished with the actual wedding yes. The problem seems to be because of DC's new stance on characters getting married, they didn't want to actually show the wedding defeating the purpose I'm assuming of the story. Thus they walked off.
Yeah, that's what I always assumed. They didn't want to finish the arc how DC wanted, so they left. There is no "letting them finish the arc," they chose to leave.
Which, actually, I'm in support of. I admire those who aren't willing to compromise and are willing to walk away rather than do so.