Is Marriage a crapshoot?

I believe it is.  When I watch those commercials for e-harmony or other electronic matchmakers, I wonder if couples matched electronically stay together longer.  I doubt it.   That kind of matchmaking has not  been around long enough to produce long term studies.  Seems to me that, while compatibility in everything from sex to money to kids to religion is important, people change over time and couples don't change at the same rate.  Will a given marriage last over the long haul?  Maybe it's the luck of the draw.