Is plural marriage obligatory for a man whose wife does not satisfy him?

Question:
A questioner says: A man is married, and his wife does not satisfy him; whenever he sees another woman, it is as if he were not married, for reasons known to Allah. His wife said: If you marry, I will divorce you. So, should he marry another without her knowledge and then tell her, even though she is very temperamental? Or, if she stands in the way, should he divorce her? And is his marriage to the second woman considered obligatory because his first wife does not satisfy him?

Answer:
If she does not satisfy him, he must marry if he is able, so he marries a second woman. If the second does not satisfy him, he marries a third, and if the third does not satisfy him, he marries a fourth; until he satisfies himself, provided he is able and has money, even if the wife does not agree. However, he should please everyone with kind words, good conduct, and justice.
So he must strive for justice, and ask his Lord to guide them and to bestow upon them approval. He should do his best, and praise be to Allah, just as the Exalted and Majestic said: [Surat al-Nisa: 3]. It is not permissible for them to oppose him in this. If she is unable—meaning: she has difficulty, distress, and cannot do it; she gives him... she gives him "permission"...