"Marriage" (or "relationships in general") to the vast majority doesn't have much to do with 'love, commitment', or more esoteric things - it's primarily simply about economic convenience and expedience, akin to a having a roommate or "kept woman".
For some it's also just a refuge of insecure souls who try to seek some type of lasting happiness solely from the external or material (physical companionship) rather than developing themselves inwardly.
In other words, it's only "sacred" to those who have an appreciation of higher things than mass society offers, while to the rest it's simply mercenary and transactionary, and even those who 'stay married' or together for long periods of time usually just do so for pragmatic reasons (e.x. loneliness, money, believe that it's 'better than nothing', etc).
So why does mass society tend to pretend to view it as 'sacred' and feign political outrage over 'infidelity' (e.x. Trump's '$#@!' comments), when to them it's really not much different than a mating ritual practiced by any other creature? Only someone truly naive would buy into their act.