All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If one makes a conditional oath to divorce his wife on the occurrence of something and he breaks that oath, then the divorce becomes legally effective, according to the opinion of the majority of the Muslim scholars. Therefore, whoever has made an oath not to do something and then violates that oath, then, in this case, the divorce becomes effective.
If one repeats doing so three times, that means that his wife gets divorced thrice; i.e., he has divorced her an irrevocable divorce (a major kind of separation in which a husband does not have any right to bring her back to conjugal life). In this case he cannot take her back as a wife unless she marries another man and has sex with that man. After that if she and her new husband separate willingly, then her first husband can remarry her as a new wife after completing all the marriage conditions. This is the opinion of the majority of the Muslim scholars. But Imam Ibn Taymiyyah is of the opinion that if a person takes an oath of divorce and then he violates that oath, the divorce will be effective only if he had actually intended the divorce at the time of taking the oath. Therefore, if a person makes an oath of divorce to emphasize something etc., without intending to divorce his wife, and then he breaks that oath, he is obliged only to pay the expiation of breaking an oath and the divorce is not considered effective.
We are inclined to the opinion of the majority of the Muslim scholars since Allah and His Prophet did not differentiate between delivering a divorce seriously, or jokingly, or delivering it at once or at different times.
For more benefit on conditional divorce, please refer to Fataawa 373048, 370447, 355693, 352696, and 328318.
Allah knows best.