God's Word makes it clear that marriage is a commitment for life to that one individual.

Jesus said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’? Matthew 19:5 (NKJV)

Sexual unfaithfulness, however, on the part of both husband and wives, has become epidemic. Adultery is a sin, but it is also a symptom that all is not well in a marriage. .

Let's read more about God's opinion about adultery...

Give honour to marriage, and remain faithful to one another in marriage. God will surely judge people who are immoral and those who commit adultery.

Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God.

Run from sexual sin! No other sin so clearly affects the body as this one does. For sexual immorality is a sin against your own body.

But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin. If we say that we have no sin, we deceive ourselves, and the truth is not in us.

He is so rich in kindness and grace that he purchased our freedom with the blood of his Son and forgave our sins.

If we [freely] admit that we have sinned and confess our sins, He is faithful and just [true to His own nature and promises], and will forgive our sins and cleanse us continually from all unrighteousness [our wrongdoing, everything not in conformity with His will and purpose].

(Jesus speaking to the woman accused of adultery).

Straightening up, Jesus said to her, “Woman, where are they? Did no one condemn you?” 11 She answered, “No one, Lord!” And Jesus said, “I do not condemn you either. Go. From now on sin no more.”

Marriage is to be held in honor among all [that is, regarded as something of great value], and the marriage bed undefiled [by immorality or by any sexual sin]; for God will judge the sexually immoral and adulterous.

The husband should fulfill his wife’s sexual needs, and the wife should fulfill her husband’s needs. The wife gives authority over her body to her husband, and the husband gives authority over his body to his wife.

Wash yourselves and be clean!

  Get your sins out of my sight.

  Give up your evil ways.

Learn to do good.

  Seek justice.

Help the oppressed.

  Defend the cause of orphans.

  Fight for the rights of widows.

“Come now, let’s settle this,”

  says the Lord.

“Though your sins are like scarlet,

  I will make them as white as snow.

Though they are red like crimson,

  I will make them as white as wool.