Does triple divorce occur for someone who swore not to commit a specific major sin but then committed it forgetfully, given a slight doubt about whether the divorce was specifically made contingent upon this major sin?

You must stay away from sins and offer sincere repentance. Your fear of Allah should be greater than your fear of divorce. If you pronounced a triple divorce conditioned on committing a sin, and then you committed it while forgetting the condition, the divorce does not occur. This is the preponderant opinion according to us. Your wife remains under your marital bond. However, the majority view is that a conditional divorce takes effect upon the fulfillment of the condition, even if the person did not intend divorce, contrary to Ibn Taymiyyah, who holds that an expiation for an oath is required in this case.