Marriage is that individual union through which man and woman by their reciprocal rights form one principle of generation. It is effected by their mutual consent to give and accept each other for the purpose of propagating the human race, of educating their offspring, of sharing life in common, of supporting each other in undivided conjugal affection by a lasting union.
Marriage is a contract and is by its very nature above human law. It was instituted by God, is subject to the Divine law, and cannot for that reason be rescinded by human law. Those who contract marriage do so indeed by their own free wills, but they must assume the contract and its obligations unconditionally. Marriage is natural in purpose, but Divine in origin. It is sacred, being intended primarily by the Author of life to perpetuate His creative act and to beget children of God; its secondary ends are mutual society and help, and a lawful remedy for concupiscence. Human law certainly takes cognizance of marriage, but marriage not having been established by man, its essential properties cannot be annulled by such law. Marriage is monogamic and indissoluble; death alone dissolves the union when consummated.
---Catholic Encyclopedia, when the biggest controversy around marriage was divorce.
"... Herod had arrested John, bound him and put him in prison on account of Herodias, his brother Philip's wife, because John had been telling him, "It is not lawful for you to have her."
--Matthew 14.4 (NRSV)
"If the world hates you, be aware that it hated me before it hated you. If you belonged to the world, the world would love you as its own. Because you do not belong to the world, but I have chosen you out of the world--therefore the world hates you. Remember the word that I said to you. 'Servants are not great than their master.' If they persecuted me, they will persecute you; if they kept my word, they will keep yours also."
--John 15.8 (NRSV)