If a Muslim sister who had already performed wudu shows her genitals to her husband has she broken her wudu and must perform it again or not?
Sexual intercourse or extreme touching.
According to Hanafis, if the skins of a man and a woman touches each other, their wudus are not invalidated(let alone seeing); however, if a woman and a man touches each other while they are naked or if they touch each other with lust without a garment that will prevent them from feeling the heat of their bodies, or if they caress and hug each other like that, their wudus are invalidated.
Most of the Hanafi scholars decide that the contact is extreme when the sexual organ of the man becomes erect; however, Imam Muhammad holds the view that unless a wetness like madi (pre-coital fluid) comes out, wudu is not invalidated.
According to Shafiis, wudu is invalidated when the skin of a woman and a man touches each other.
According to Malikis and Hanbalis, wudu is invalidated if sexual pleasure is felt when the skins touch each other.