Why are so many long term marriage couples divorcing?

Perhaps because of problems that are always held. Finally, after the passage of time, the problem can not be detained. And finally decided to divorce.

maybe they get bored with each other?...

Times are stressful. Finances are a big problem in a lot of marriages. And, a lot of women are starting to see that there they have other options than to stay in a relationship that doesn't fulfill them. Also, deviant behavior is running rampant in today's society. So, straying morally - cheating, lying, addictions, etc.

Maybe after that long, things still haven't changed so they finally break free. Or maybe they feel that it is their last chance to follow their hearts so they break free.