Today, conditional marriages are discouraged, if not entirely disallowed. The Mishna (72b), however, discusses cases where a person made the marriage conditional on the fact that his wife does not have vows that she has taken on herself or physical deformities. In such cases, if the woman is found to have such vows or physical deformities there is no need for a divorce, since the condition upon which the marriage was based was not fulfilled.
What if the husband made such a condition at the time of the kiddushin (betrothal), but then completed the marriage (nisu’in – which during Talmudic times was often a year later) without stipulating that the condition be fulfilled? In such a case we find a disagreement between amoraim. Rav requires that a divorce be given; Shmuel says that there is no need for a divorce, since the condition upon which the marriage was based was not fulfilled.
According to Rabba, both Rav and Shmuel agree that in a normal case where a condition is stipulated at the time of the kiddushin, the condition will remain binding even if the nisu’in was completed without a restatement of the condition. Their disagreement is only in an out-of-the-ordinary case – a situation of two wives.
What is the case of “two wives”? According to Rashi, the case is where a man married one woman and stipulated that it was conditional and then married a second woman without making that same condition. Must we assume that his first statement should be understood to refer to all of his marriages or not?
The rishonim take issue with Rashi’s approach and offer other explanations for this case. The Ri”f suggests that we are talking about a case where the man has kiddushin with one woman that included the condition, and with a second woman without any condition. When he completes the marriage (nisu’in) with the first woman, can we view the unconditional kiddushin with the second woman as an indication that he no longer cares about this issue? The Ge’onim take an entirely different approach. According to Rav Natrenai Ga’on the case of “two wives” is when a man offers conditional kiddushin to a woman, but then finds that he has married another, with whom he had made no conditions.