There are no statistics on dating/marriage outcomes, because, as anyone who has tried to do social research in the frum community knows, few people will tell the truth, and many will simply refuse to answer. And we have no practical way of designing a study anyway. The only good data that I’ve heard about have come from rabbonim and batei din, and they don’t collect the kind of information needed.
And for anyone who’s done any research, you know that “data” is not the plural of “anecdote.” No matter how many times you hear something at the kiddush club or from your brother-in-law, it does not mean that you can assume it represents what’s happening in the whole community. There are probably many happy marriages where one or both spouses have a “problem” but they know how to handle it, in which case you’ll never hear about it. Maybe the batei din in Lakewood could come up with some way of collecting data, but in the meantime we’re flying in the dark.