1) Chastity is the virtue that engages the erotic dimension of relationships, integrating it with respect for the whole person, which can only take place in marriage.
2) Though it involves a “no”, it’s in service to an ultimate “yes” of giving and accepting the gift of another in relationship.
3) Without chastity, it’s impossible for a person to make a total gift of self in marriage or a partial gift of self in any other relationship.