God has provided the basis for marriage at the beginning of book of Genesis in the story of man’s creation.
Adam was alone and so God created the woman (Eve) to be a good companion to save Adam from his loneliness.
Marriage is an objective truth in the Bible and we, as followers of Jesus Christ, live by the fact that we choose a healthy marriage.
God has chosen and called some to singleness. The rest of us need companions in our lives, so that we can glorify God in our lives together.