Divorce in the case of adultery (Matthew 19:9)
All faithful Christians (including Catholics) agree that the Bible is the infallible word of God. This applies to the original Greek Bible, not the 100's of translations of the Bible over the centuries. When there are discrepancies, we need to go back to the original Greek, and we also need to look at how the passage in question has been understood in Christendom over the centuries.
New Evangelical Bibles translate "porneia" as "adultery" not "fornication"
When there is a departure from the traditional understanding, we have to ask ourselves "why?" The modern NIV translates Matthew 19:9 as:
I tell you that anyone who divorces his wife, except for marital unfaithfulness [Greek: porneia], and marries another woman commits adultery." (Matthew 19:9, Modern NIV)
This translation and other modern protestant translations have shifted the traditional translation of the Greek word porneia from "fornication" to "marital unfaithfulness" which is adultery. But the Greek words for "adultery" is naaph or moicheuo.
Most older Protestant Bibles, including the King James Bible, Wycliffe, American Standard, New King James, Darby, Gutenberg Bible, the ancient Latin Vulgate (400 A.D.), the Douay-Rheims (Catholic), Strong's Greek Commentary, and Vines Biblical Exposition translate Porneia to "fornication".
Historical translations get it right, including Protestant versions
The King James Bible follows the Catholic translation of Matt 19:9
"And I say unto you, Whosoever shall put away his wife, except it be for fornication [Greek: porneia], and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery." (King James Bible, Matthew 19:9)
This difference in translation is incredibly significant because "fornication" is a specific type of sex relation where neither person is married. Jesus was saying that the first marriage was a fornicating relationship, and that they were not truly sacrementally married. The marriage is null and void, or annulled. This relationship is prefigured in the Old Testament's story of Abraham's (legitimate) marriage to Sarah, and his (illegitimate) relationship to his concubine Hagar. (Gen 21)
When considering the King James translation, one would think that the 16th century King of England would want to support divorce, since the previous King, Henry VIII, created the Church of England by forcefully splitting from the Catholic Church when it didn't grant him an annulment. Yet the KJV supports the Catholic translation. The Catholic New American Bible translates Matthew 19:9 as:
...whoever divorces his wife (unless the marriage is unlawful) and marries another commits adultery. (NAB)
Yes its a hard teaching, no divorce, no remarriage
It is a hard teaching that allows no divorce, no remarriage, and no exceptions unless the first "marriage" was a "fornicating" marriage that was not recognized under God, which is an annulment. This is supported by the next line where the disciples are perplexed at how hard this was :
"If that is the case of a man with his wife, it is better not to marry." (Matthew 9:10)
And Jesus didn't say anything like "well you can be forgiven and marry again", which is what many of the Evangelicals say even though they concede that marriage is indissoluble. Jesus basically said marriage is very hard, and that many are called stay celibate (Mat 19:11-12).
Evangelical exception for "adultery" encourages adultery
The other problem with the modern Evangelical exception for "adultery" is that it defies logic. It would actually mean that Matthew was sending a signal to Christians that if they did want a divorce, all they would have to do is have sex outside of marriage. The disciples' response to Jesus' words do not support that interpretation. There is a kind of rationalization among many Evangelical Churches today that says, "the Lord will forgive me for my adultery, and then I will be free to marry someone else." On the surface this seems like a small price to pay to get out of an unhappy marriage. However the long term implications and consequences are beyond our imagination. We don't think Jesus would ever leave that kind of loophole. This phenomenon has only popped up since recent Protestant Bible translations started interpreting Mat 19:11 this way.