I have the new wedding pack. My Sims were engaged, and I did the whole ceremony twice. The first time I thought it was my mistake because maybe I interrupted them while exchanging vows, but the second weeding that I planned I noticed it was a glitch because it did matter how many times I made my sims exchange vows to get married before they tied the knot (so pretty much after exchange the rings) they would reset themselves and cut the action.
I tried it at the wedding venue and by themselves, with the officiator, and without it. The event ended, and they weren't married. Only when the event ended could I marry them; I couldn't otherwise.
Don't know if others are having the same issue, but even before I know there's been issues with the weddings.