I thought that the vow was typically, "until death do us part" in which case the vow would be broken.
The only thing that I've seen go against this was my best friend's wedding. I was the best man, so I was close enough to hear the slight difference in the sermon, so most of the family heard it.
When it got to the point where he says "as long you both may live" he said "as long as you both may love". If that's not a way to just cheapen the whole thing and give an easy way out, I don't know what is.
But still, assuming the marriage was completely traditional, there is no reason to think she shouldn't be completely free to date after 2 years.
I would agree that dating a month or two later would be disrespectful, but at the same time, she is entitled to enjoy the rest of her life as well, and I think plenty of time has probably passed for that.