I know years ago men left women....but these days I think it's the opposite....
What say OG? 
based ony my dealings with my work clients and people i know
the majority of the time, it's the woman choosing to leave the man
the reasons for leaving vary from case to case though...many justified, many times it's cuntiness, other times you really dont know the entire story
but id say the current state of divorce law and custody law make it way eaasier for the woman to leave if she chooses
It seems to be at least where I live. There are so many more men than women they just seem to "upgrade" like trading in a car. 
For me I have observed an even split. It might even go in favor of the men leaving.
significantly more common.
i think it's 70+ % with women leaving.
Regardless of who is at fault, or whoever is the cause of ending, men are more likely to want to work things out, or just afraid of a divorce because, they usually lose.
The way the incentives are set up, it's no surprise wives leave husbands. The contract essentially boils down to "The courts will pay you X hundred thousand dollars to leave your husband". When you create a direct monetary incentive for women to leave men, it's going to cause break ups. The courts are sexist and men often earn more, hence the asymmetry.
For boyfriend/girlfriend from anecdotal evidence I'd think it was usually the men leaving the women.
It's women by a WIDE margin....more than 2 to 1 by divorce stats. But people have been perpetuating the myth of "men leaving" as the #1 problem for a long time. It has led to a lot of brutal inequities in Family Court.
I've noticed that in my circle of people I know it know about, the women tend to leave and worse they cheat on their husband to set up the next guy before they do the divorce. Very cunty of them.
Like others have said, women by quite a bit and they always wait until another sucker is in their cross hairs.
Men will stick around and remain miserable so they dont hurt their delicate little flower (they may cheat while doing so).
in
70% of divorces are filed by women...
Tinerrz - 70% of divorces are filed by women...Wow.
shit lot of women are making more than men so i can see them leaving.
Provided they have another lily pad to jump to, it's women
Meastt - I know years ago men left women....but these days I think it's the opposite....
What say OG?
I think a man is more likely just to stay married indefinitely but cheat constantly.
A women is more likely to swing from one cock to the other like tarzan, where she doesnt quite let go of the last one until she gets a grip on the next one.
So she will cheat for a little while, then file for divorce, and move in with the new guy.
Are we talking marriage? OP was not specific. What about non-married but serious / exclusive couples?
iclimb513 - Are we talking marriage? OP was not specific. What about non-married but serious / exclusive couples?
an interesting question. I for one, am not signing any contract.
most divorces are initiated by the woman.
it makes sense because they can benefit monetarily from the divorce as men generally make more money.
also, even men who cheat around want to stay in a marriage for social purposes.
as for dating, it's possible that women leave men more, but a lot of times men don't want to be the bad person so create the situation for the woman to leave them.
The way the system is set up now, a man would be crazy to leave a woman.
american men have been taught to go against other men in a darwinian way, while white knighting for every woman out there.
Of course the situation has come to this.
NO fault divorce is just crazy.
There must be at fault divorce to remedy the increasing social ills in the US.
People who grow up in 2 parent families are generally more well adjusted. It's the way NATURE INTENDED.