Urban II in JL 5399 = Gratian, Decretum C. 31 q. 2 c. 3
De neptis tuae coniugio, quam te cuidam militi daturum necessitatis instante articulo subfidei pollicitationefirmasti, hoc equitate dictante decernimus, ut, si illa uirum illum, ut dicitur, omnino renuit, et in eadem uoluntatis auctoritate persistit, ut uiro illi prorsus se deneget nupturam, nequaquam eam inuitam et renitentem eiusdem uiri cogas sociari coniugio. Quorum enim unum corpus est, unus debet esse et animus, ne forte, cum uirgo fuerit alicui inuita copulata, contra Domini Apostolique preceptum aut reatum discidii, aut crimen fornicationis incurrat. Cuius uidelicet peccati malum in eum redundare constat, qui eam coniunxit inuitam. Quod pari tenore de uiro est sentiendum.
[Concerning the marriage of your niece, whom you declare that you have promised under oath will be given (because of urgent necessity) to a certain knight. We decree, as fairness demands, that if (as reported) she totally rejects that man, and willfully persists [in her rejection], so that she altogether refuses to marry him, you may in no way force her, unwilling and objecting, to be joined to that man in marriage. Those who are of one body should also be of one mind, lest perchance a young woman joined to someone against her will may risk the guilt of desertion (against the command of the Lord and the Apostle) or the crime of fornication. It appears indeed [that] the evil of the sin spills over onto him who married the unwilling woman. Much the same may be held concerning a man.]
Trans. James A. Brundage