If she tells the husband "I want a divorce", big deal! They all say that when they get angry. So it's not really a serious fight, and when she cools down it's OK. But if she tells the husband "you divorced me" that's a serious fight. But if that's the case then you should believe her, because Rav Hamnuna said that if a wife tells the husband "you divorced me" we believe her, because chazaka that a wife is not a mechutzaf to the husband. So the answer is that she said "you divorced me in front of so and so", and we asked them and they said "it never happened" (Yevamos 116a).
So there you have it folks. Asking for a divorce is not a big deal. It just shows that you shouldn't expect marriage to be one big lollipop.
I just heard on Zev Brenner that Lakewood has like 30 divorces per month, and I also heard this from another source. I'm not sure exactly whats going on since I don't do shalom bayis (I wish I would). But I did hear that the divorced community is shtuuping each other, and they're not really happy because they're not getting a loving relationship that you get with a long term marriage.
You wouldn't believe how many guys think that this "Needa" business is only by married women, and once a woman gets divorced she is no longer a Needa.