1 Corinthians 7
1 Now for the matters you wrote about: It is good for a man not to marry.
2 But since there is so much immorality, each man should have his own wife, and each woman her own husband.
3 The husband should fulfill his marital duty to his wife, and likewise the wife to her husband.
4 The wife's body does not belong to her alone but also to her husband. In the same way, the husband's body does not belong to him alone but also to his wife.
5 Do not deprive each other except by mutual consent and for a time, so that you may devote yourselves to prayer. Then come together again so that Satan will not tempt you because of your lack of self-control
And actually, the entire chapter has some good stuff in it. BTW this is NIV.