Does divorce take place if a man says to his wife, "If you come to know a man other than me, then you are divorced," and she had known a man before marriage and continued her relationship with him after marriage?

The ruling on the occurrence of conditional divorce depends on knowing the husband's intention and what he meant by what he uttered; whether he intended to condition it on an existing or future relationship, and whether he intended to effect the divorce or merely threaten. The preponderant view is that intention specifies the general لفظ (utterance), and conditional divorce occurs upon the fulfillment of the condition, whether he intended thereby to effect the divorce or merely threaten. Some scholars, like Ibn Taymiyyah, hold that conditional divorce intended as a threat does not occur, and an expiation for breaking an oath (kaffarat yameen) becomes obligatory. Due to the difference of opinion, the matter must be presented to scholars.