From Matthew 19: 1 - 9
When Jesus had finished saying these things, he left Galilee and went into the region of Judea to the other side of the Jordan. 2 Large crowds followed him, and he healed them there.
3 Some Pharisees came to him to test him. They asked, “Is it lawful for a man to divorce his wife for any and every reason?”
4 “Haven’t you read,” he replied, “that at the beginning the Creator ‘made them male and female,’[a] 5 and said, ‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’[b]? 6 So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”
7 “Why then,” they asked, “did Moses command that a man give his wife a certificate of divorce and send her away?”
8 Jesus replied, “Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. 9 I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery.”
The Apostle Paul taught this in Corinthians 7:13 - 15:
13 If any woman has a husband who is an unbeliever, and he consents to live with her, she should not divorce him.
14 For the unbelieving husband is made holy because of his wife, and the unbelieving wife is made holy because of her husband. Otherwise your children would be unclean, but as it is, they are holy.
15 But if the unbelieving partner separates, let it be so. In such cases the brother or sister is not enslaved. God has called youb to peace.
There are your two (and only two) biblical reasons for divorce according to Scripture.
The Pauline privilege is a special case, in which no sacramental marriage was existing. As for your supposed loophole for adultery, you will have to reconcile it with Mark 10; Luke 16; and 1 Corinthians 7 where Paul allows an unfaithful wife to be put away, but with no warrant to remarry.