What should you do with your fiancé who does not lower his gaze, and what is the impact of that on you, and what is the punishment for not lowering his gaze?

If your suitor does not lower his gaze from the unlawful, advise him and remind him of the virtue of lowering the gaze and the words of the scholars regarding it. If he does not desist, then you have fulfilled your duty. If he is sincere in his attempt to lower his gaze, then marriage will help him. The suitor is a stranger to his fiancée, just like all other strange men.