From the Council of Paris, A.D. 615

Canon XIII. Concerning widows and girls who, in their own houses, whether by their parents or by themselves, have changed their clothing into the habit of religion, and afterward, against the statutes of the Fathers or the precepts of the canons, have believed themselves to be coupled in marriage: let both be held suspended from communion so long as they amend what they have unlawfully perpetrated; or if they have neglected to amend, let them be sequestered forever from ecclesiastical communion or the banquet of all Christians.

Religious profession was still then permitted to virgins and widows in their own house according to the old custom. Cf. the preceding canon.

Thus Sirmondus edited the canon just now recited. But Baluzius (in the Capitularies of the Franks), referring from the same Council an edict of King Chlothar on this matter, thus presents it under n. XVIII: Religious girls and widows or nuns, who have vowed themselves to God, both those who reside in their own houses and those who have been placed in monasteries: let no one either claim them by our precept, or drag them away, or presume in any way to associate them to himself in marriage. And if anyone has elicited a precept concerning this (that is, has obtained it from the king), let it obtain no effect. And if anyone, either by force (that is, violence) or by any order, has presumed to draw them away or to associate them to himself in marriage, let him be struck by capital sentence. And if they have made marriage in the Church and that abducted woman, or she who is to be abducted, seems to consent to this, let them be deported into exile, sequestered from each other, and let their properties be joined to their nearest heirs.

But the sixth Council of Paris, A.D. 829, forbade to women these religious professions in their own houses. But cf. Canon XXIX of the Roman Council under Eugene II, A.D. 826.

Canon XIV. We have judged that incestuous unions are specially to be cut away from the whole Christian people, so that if anyone has believed that the widow of his brother, the sister of his wife, his stepdaughter, a female cousin, a cousin's daughter, or likewise the widow of his paternal and maternal uncle, or one given in the habit of religion, is to be violated by the consortship of marriage, let him be segregated from the grace of communion so long as he ought to abstain by most manifest separation from unlawful unions.

You see that the marriages of religious women are numbered among incestuous unions.