Yeah I agree there is no reason for each one to hide something especially if married for a long time because if that happen I know something is wrong and I don't tolerate that kinda thing. That really is betrayal for me and that can ruin trust.
I say that there can be many bad things that people can do to others, but betrayal is the worst of all for me because it includes lies, bad acts and many things that should not be done to anyone, so in operation when a person betrays me, then they are not taken into account for anything else in the world, with me they lose them all and if it is the partner, then even more, just like there are so many good people in the world that one cannot be sleeping with the enemy.