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.