The whole wedding thing always seemed like foreshadowing for a future game to me, since nothing else is really mentioned about it in DF.
The third TES game was originally going to be called
The Elder Scrolls III: Tribunal and would've taken place on the Summerset Isles. This was obviously pushed aside due to Bethesda's desire to wait for more advanced technology before pursuing their third primary TES game, and they were busy working on Battlespire and Redguard in the meantime. Obviously the third proper Elder Scrolls game became Morrowind, Tribunal's design premise slashed but its name lived on through the Temple established in Morrowind, as well as its expansion of the same name. You can find all the information about this original plan for TES3 http://www.elderscrolls.com/tenth_anniv/tenth_anniv-morrowind.htm.
I never thought about this and the wedding invitation side-by-side before, but you may be right. Perhaps the invitation was meant to be a hint towards the third game?