Thomas Aquinas

“ Further, unlawful intercourse after marriage is more guilty than before marriage. Now if a wife, after the marriage has been consummated, has intercourse with another man, her husband does not become irregular, otherwise he would be punished for his wife's sin. Moreover, it might happen that, after knowing of this, he pays her the debt at her asking, before she is accused and convicted of adultery. Therefore it would seem that this kind of bigamy does not cause irregularity. ”

“ There is, however, a difference, because on the part of the husband it is required that he should not have married another wife, but not that he should be a virgin, whereas on the part of the wife it is also required that she be a virgin. ”

“ Wherefore others say that Christ is signified by the bridegroom, and that the bride signifies the Church triumphant in which there is no stain. Also that the synagogue was first united to Christ as a concubine; so that the sacrament loses nothing of its signification if the bridegroom previously had a concubine. But this is most absurd, since just as the faith of ancients and of moderns is one, so is the Church one. Wherefore those who served God at the time of the synagogue belonged to the unity of the Church in which we serve God. ”

“ Wherefore since concupiscence is most incompatible with spirituality, inasmuch as it makes a man to be wholly carnal, they should give no sign of persistent concupiscence, which does indeed show itself in bigamous persons, seeing that they were unwilling to be content with one wife. ”