I am a Southern Baptist whose daughter is cohabitating with her Catholic boyfriend. Does Catholicism endorse unmarried couples living together?

The Catholic Church rejects cohabitation outside of marriage. The Catechism states, "All the baptized are called to chastity. The Christian has ‘put on Christ’ (Gal. 3:27), the model for all chastity. All Christ’s faithful are called to lead a chaste life in keeping with their particular states of life. At the moment of his baptism, the Christian is pledged to lead his affective life in chastity" (CCC 2348).

It further states, "Those who are engaged to marry are called to live chastity in continence. They should see in this time of testing a discovery of mutual respect, an apprenticeship in fidelity, and the hope of receiving one another from God. They should reserve for marriage the expressions of affection that belong to married love. They will help each other grow in chastity" (CCC 2350).