Is a husband entitled to marry a third wife on the grounds of his second wife's illness, knowing that he does not approve of her treatment, and is the second wife's consent necessary?

It is the husband's right to marry a third woman without requiring his wife's consent, unless she stipulated in the marriage contract that he should not marry another woman while married to her. In that case, she has the right to annul the marriage.

It is forbidden for the wife to refuse intimacy with her husband without a valid excuse, for Abu Hurairah (may Allah be pleased with him) narrated that the Prophet (peace be upon him) said: "If a man calls his wife to his bed, and she refuses to come, the angels curse her until morning."

Scholars differed regarding the obligation of the husband to spend on his wife's medical treatment, and the preponderant opinion is that it is obligatory according to what is customary.

The advice is for the wife to treat her husband kindly and not to refuse intimacy without a valid excuse, and for the husband to strive for his wife's treatment, treat her kindly, and be keen on dealing justly between his wives.