How do you know your marriage will last?

No one really knows for sure....it is what you make it.  Love each other for who you are, and as you and your spouse evolve continue the tradition of love.  Trust and respect are huge factors as well.  People have made billions of dollars over the years trying to explain women to men, then explain men to women, to teach love and respect....blah, blah, blah.  I'm not going to get up on the soap box and tell you how to hang on to your mate.  Everyone is different....some are more DIFFERENT than others.............
But, if you must have a tangible test of the longevity of a marriage....renovate your kitchen.  Not with hired help.  Not while you are on vacation.  Not with a giant group of friends.  Do it together from start to finish.
In the beginning (just like young love) it's fun, you have plans, it's exciting, you have money to spend.  You dream together and marvel at how wonderful it is to have the opportunity to spend such quality time together.  And really, tearing things apart with crowbars and stuff is damn fun....and what a stress reliever. Phase one will be great.  Then you have the discovery phase.  All the stuff you feared is now exposed.  You didn't plan for new wiring or new plumbing.  The honeymoon is over.  You are both right, and you are both wrong; just not at the same time.  Plans are changing.  Things are starting to go awry.  The whole project takes a lot more time, energy, money and patience than anyone had every expected.  This whole "quality time" crap is just that...crap.  Like really, who needs to spend that much time together??? After a while, you come to accept things for what they are.  Plans change all the time, you have to roll with the punches.  The project begins to mature, and it starts to look like the original plan.  This sets your heart a pitter-patter.  Could this be love?  Is this the way its supposed to be.  Then the bills start arriving.  You are way over budget, way over.  Anger sets in.  Who needed a new damn kitchen anyway?  Now we have a half finished room with a tonne of bills and no end in sight.  You quietly continue on; seething, but smiling on the surface because you are supposed to be happy about the new damn room.
In an attempt to finish the job - the reveal party date is set.  (this would be the marriage counsellor part - do or die).  The push is on, the job gets done.  All the tension is gone.  It was worth it.  We stand back together and marvel at our accomplishment; while in our heads counting how many times we each would have loved to have walked out the door and never returned.
And here today, the day after - we lie on separate sofas - hungover - yet in love with each other and the new baby we created - OUR KITCHEN.