Whether people change in marriage or you just didn’t know them well is neither here not there, but the fact is that not matter how well you think you know your partner sometime in the journey of marriage they will reveal a certain character trait that you didn’t know about.
Many of the frustrations in marriage are the results of thinking that you know a person, how they are, and how they behave, but then when you see or find out things that you never expected, you either in denial, crashed, discouraged or keep trying to get the person to change.
There is need for someone to accept what there have, it a lair, a cheat, a gossiper, a hater, etc. Marriage succeed best when people follow Christian principles, but even if people are not Christians marriage can still continue.
There is a vow that people make when they get married, it promises certain things to the spouse, to love to cherish, to be there in sickness and health