Halachic authorities list a man not looking at his unclothed wife as one of the harchakot, rules of conduct during niddah. This is intended to prevent him from having sexual thoughts that might lead to action.

There is no parallel discussion in classic halachic literature of wives looking at their unclothed husbands during niddah. That leaves room for this to happen incidentally, without erotic intent. If, however, a woman knows that seeing her husband undressed is likely to have an arousing effect on her, then she and her husband should avoid it.

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