All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If this man divorced his wife one or two times only, then he may remarry her with a new marriage contract, and the condition that she marries another man first does not apply in this case. However, if he divorced her three times, then that is an irrevocable divorce with major separation. There is no way for him to remarry her except if she married another man (in a genuine marriage, not a Tahleel marriage for the sole purpose of legalizing remarrying her ex-husband), consummated marriage with him, and he then happens to divorce her or passes away. In this case, her ex-husband may remarry her after her ‘Iddah (waiting period) ends. Please refer to fatwa 134069.
Allaah knows best.