Well, this is the worst case scenario that any photographers will face - No lights. The candles generally won't be bright enough to lit the couples in a creative way, the bride and the bridegroom will still look severely underexposed, because there is just insufficient light illuminating them.
Any experienced photographers will tell you - No light = No Photography.
That is where we are left with 2 options to create light.
1. Either you have to negotiate with the hotel/restaurant manager to use at least some sort of a spotlight to create a romantic/grand feel. Let's face it. It's not just about your photographs. It just doesn't make sense if the guests couldn't be able to see the lovely bride where she would have already spent more than 2 hours with make-up to make herself look pretty during the wedding march itself. You can still go without flash.
2. Yes. Use a flashgun. I'm not joking. I'm serious. That's the last resort you have to take when all else fails.
Flashgun, contrary to many beliefs, makes a photo look harsh and unnatural, very cave-like. However, if flash is used correctly, could yield very interesting results. Think studio lighting. If you position your flash in such a way it illuminates your subject in a directional way (maybe from sides, etc), it can yield artistic results. Also if the flashgun is used correctly, it can dramatically create the mood of the shot while not ruining it.
It's really hard for me to capture this kind of photo (btw, Im not the photographer of tat photo). Tripod is out of the question since the subject is constant moving. Need to find out what are the usable ISO with acceptable noise. I would use fastest lens at disposal for exposing enough lights and use a continuous focus and burst mode. I can't think of better dslr for the job except D3S. Correct me if I'm wrong.