Husband and wife generally don't have anything to hide but it depends on the couple and level of trust. My husband and I when home majority of the times use the phone which is nearby- could be his or mine. We both have work phones and he never checks mine and I never check his - it contains private client information. We would never check that phone because there is no need.
Also I think if a man is going to cheat he will take better measures than our resident idiot kunal. That guy only lies both to his wife and girlfriend!!!