פירוש על קידושין 99:16

It can be assumed that a husband does not want his wife to be subject to vows that will prevent her from engaging in certain activities, such as eating meat or drinking wine. Such vows would certainly disrupt the normal functioning of a marriage. If he betroths her on the specific condition that she is not subject to any vows, and after betrothal it is found out that she is subject to vows, she is not betrothed. Since the betrothal was made under false pretenses it is invalid and she does not need a get to remarry, nor does she receive her ketubah. However, if he did not make such a condition, and then later finds out that she is subject to vows, the marriage is valid. Nevertheless, since she should have told him that she had vows, he may divorce her without paying her the ketubah. In other words, the marriage was not exactly made under a false assumption and therefore she needs a get in order to remarry, but she still was dishonest with him and therefore she loses the ketubah.