Is there a secret,or is it natural chemistry and symbiosis?My grandparents were married for over 60 years,some relationships are more durable than others,some marriages flounder on the rocks within a year,i have seen a few on here that didn't have decent foundations and perished,who knows the answer,its human beings,theres no mathematical calculus nor chemical formulae to predict who is going to last the distance and which couple will fall at the first hurdle