Here’s what the catechism says about homosexuality:
2357 Homosexuality refers to relations between men or between women who experience an exclusive or predominant sexual attraction toward persons of the same sex. It has taken a great variety of forms through the centuries and in different cultures. Its psychological genesis remains largely unexplained. Basing itself on Sacred Scripture, which presents homosexual acts as acts of grave depravity,141 tradition has always declared that "homosexual acts are intrinsically disordered."142 They are contrary to the natural law. They close the sexual act to the gift of life. They do not proceed from a genuine affective and sexual complementarity. Under no circumstances can they be approved.
2358 The number of men and women who have deep-seated homosexual tendencies is not negligible. This inclination, which is objectively disordered, constitutes for most of them a trial. They must be accepted with respect, compassion, and sensitivity. Every sign of unjust discrimination in their regard should be avoided. These persons are called to fulfill God’s will in their lives and, if they are Christians, to unite to the sacrifice of the Lord’s Cross the difficulties they may encounter from their condition.
2359 Homosexual persons are called to chastity. By the virtues of self-mastery that teach them inner freedom, at times by the support of disinterested friendship, by prayer and sacramental grace, they can and should gradually and resolutely approach Christian perfection.
So, homosexual action and behavior is not acceptable and is a sin. Having a homosexual orientation, however, is tolerated AS LONG AS one resists it and does not have any type of homosexual relationship; homosexual orientation is tolerated but should be eliminated. That means homosexuals should strive to “master themselves” by fighting homosexual attraction etc., just as a heterosexual person would avoid giving in to heterosexual attraction if he decides not to marry, or if he marries and aims to be faithful to his spouse. Even if one planned to marry as a heterosexual, one would want to be self-controlled and avoid letting attraction overcome his mind. Since homosexual marriage is impossible (since God would never join two homosexuals), it is never appropriate for a homosexual to passively tolerate his attraction for the same sex.