A.T. Robertson Commentary 1 Corinthians 7:2

"But, because of fornications, let each man have his own wife, and let each woman have her own husband." — 1 Corinthians 7:2 (ASV)

Because of fornications (δια τας πορνειας). This is not the only reason for marriage, but it is a true one. The main purpose of marriage is children. Mutual love is another. The family is the basis of all civilization. Paul does not give a low view of marriage, but is merely answering questions put to him about life in Corinth.