"No doubt with other men she becomes another woman: la donna è mobile."
La donna è mobile (woman is flighty/fickle) is one of the most well-known arias in the world and is sung by the tenor voice of Duke of Mantua, in Giuseppe Verdi's opera, Rigoletto. In the song the Duke laments the fickleness of women, while recognising he can't live without them. The words can be regarded as ironic, in the context of the story, as it's the character of the Duke who is shown flitting from woman to woman as he seeks to satisfy his own desires.
To listen to the piece sung by Luciano Pavarotti, on Spotify, click here.