Islam recognises the permissibility of a man having four permanent and concurrent wives.  The man’s second marriage while he has a permanent wife, except in the case of marriage with the wife’s niece (her brother’s daughter, or sister’s daughter)[1], is not conditional upon consent of the first wife. But, if the wife [stipulates], as a condition of the marriage, that her husband cannot marry another woman, then, according to some jurists (Fuqahā)[2], this condition is valid and the husband should not violate it.

Of course, in the new family support law there is an articles which is as follows[3]:

Man cannot marry another woman while he has a permanent wife, except under the following conditions:

1.       Consent of first wife,

2.       Inability of the first wife in performing matrimonial duties,

3.       The wife not  offering herself to the husband,

4.       The wife suffering dementia or other incurable diseases,

5.       The wife sentenced to prison,

6.       The wife being addicted to narcotics or drug addiction,

7.       Infertility,

8.       The wife abandoning the family, etc.

On the other hand though, it is stipulated in marriage contract today (in Iran), that if the man marries another woman without his first wife’s consent, she (the first wife) has the right to request a divorce[4].

As for your second question:

Since marriage is a divine and eternal union, and only one of its objectives is to control lust, other affairs, such as: peace of mind, production of offspring, etc. are [also] objectives of this blessed union. With careful planning in selecting a suitable spouse, one should set the grounds for a continual cohabitation along with tenderness and compassion, and one should try to marry based on attraction, [otherwise] if the marriage has been conducted without attraction and love, then one should to try to create attraction and love in it. Obviously, the intention of a person, in the reason for marriage, has no effect on whether it is valid or not; nevertheless, God will reward every action that is for His sake.

Indeed, if there is unwillingness and force, then that is a different matter. The author of the book "Kalamatul-Taqwā" says: “Any contract (aqd) that has been carried out by force, is binding. In other words, if someone is forced to execute a marriage contract for someone else, given that the other conditions of the validity of the contract are met, it will be valid and binding; meaning that just because one was forced to carry it out doesn’t mean that it won’t be valid. But, if someone is unwilling to execute a marriage contract relating to himself, and in this state of unwillingness, all other conditions of the contract are met, it will still be invalid. However, if afterwards, the unwillingness disappears and that person becomes content with the marriage, it will be valid, and it does not matter, in its effect, that the unwilling person is husband or wife[5].

Ayatollah Mahdi Hadavi Tehrani (dāmat barakātuh) in response to the above question is the following:

1.       In the second marriage, the consent of the first wife is only required if a person wants to get married to the first wife’s niece (her brother’s daughter, or sister’s daughter).

If, during the first marriage contract, a condition was stipulated that other marriages can [only] happen with the permission of the [first] wife, to fulfil ones duty, acting upon this condition is necessary [or else one has sinned], however the marriage is valid and even though it is without permission, unless the law of an Islamic country (system of Walāyat Faqīh) declares this marriage invalid.

2.       Heartfelt attraction is not involved in the validity of a marriage, however, there is not doubt that it is required for survival and social wellbeing of marriage.

Related response: 3103 (Site: 3368).