I read in the catechism that marriage is indissoluble. Why then does the Church issue annulments?
Sacramental marriage is indeed indissoluble. You can find this in several places in the Catechism of the Catholic Church. Indissolubility is foundational to the union of marriage (CCC 1646) and required by spousal love (CCC 1644). This quality of marriage draws its meaning from the fidelity of Jesus to his Bride, the Church (CCC 1647). Spouses give themselves forever to each other. Through the vows and their consummation, the spouses form a covenantal bond that binds them as one. Indissolubility presumes and depends on this sacramental bond between the spouses.
Sometimes, however, there are impediments to marriage that are overlooked, poorly understood, or unknown. It is possible that at the time of the vows, something was either present or absent that made the consent invalid. The ceremony itself does not bring about the sacrament. The priest is the official witness of the Church, but he is not the minister of the sacrament. The husband and wife are the ministers of the sacrament to each other. Without the full, free, and able consent of the man and the woman, no sacrament takes place. An annulment does not destroy the marriage bond. It is an