How can complete repentance from the "zina of the gaze" be achieved, especially when dealing with unveiled women in the West, considering the difficulty of completely lowering one's gaze while speaking to them or in daily situations, and will repentance be accepted if there is a possibility of returning to this sin in the future?

You must lower your gaze from anything that incites fitna. If your gaze falls upon a non-mahram (definition) woman, immediately avert it. Strive in this and seek Allah's help. Repentance from unlawful looking involves ceasing the act, feeling remorse, and resolving never to return to it. A sound repentance is not invalidated by falling into the sin again; rather, you repent from the second transgression. Do not let your fear of being accused of extremism prevent you from lowering your gaze. If you find it difficult to lower your gaze from the faces of some female relatives and you are secure from fitna, some scholars have permitted it. Indeed, some scholars believe that looking at the face of a non-mahram woman is not forbidden if fitna is not feared, and this is the view of the Shafi'i school. Lowering the gaze is among the most beneficial actions for safeguarding one's chastity and rectifying the heart.