Alhamdulillah wassalamtu wassalamu 'ala rasoolillah.
Islam is a pragmatic religion - practical in all aspects. If one were to delve into the minutae of the methodology of Islamic Law (Usool al Fiqh), one would find that it has taken into account the not so subtle realities of life - that this life is not a bed of roses. That life after all is not just looking for Prince Charming or Cinderalla and live happily ever after. That one goes to a series of vascillating ups and downs and twists and turns. These, perhaps, serve to remind us that hey - this is not Jannah bro/sis! This is the fleeting Dunya, don't fall inlove with it.
Although one can say that these things did not happen to me or to my family, but how many neighbors or your dentist's neighbors you heard having illegal extra marital affairs? How many broken families were direct result from these affairs? Isnt it better to absorb and build families rather than breaking it apart? Statistics my friend. Statistics will tell us all. There are hundreds of thousand more women than men in New York [1.5% of 19 million people] (http://quickfacts.census.gov/qfd/states/36000.html). Tell me how are these hundreds of thousand women fulfill their socioeconomic, emotional and physical needs? How many mistresses, girlfriends and prostitutes amongst these? The FACT that there are women who allow themselves to become mistresses and prostitutes points to the reality that these women may also allow themselves to become a wife of an already married man. ISnt it more honorable and sustainable to become a wife with all the rights of the first than to be a mistress?
Before I proceed, it is perhaps beneficial to classify whatever in this Dunya into four things:
1. Absolutely Beneficial with no harms
2. Overwhelmingly beneficial - with benefits outweighing the harms
3. Overwhelmingly harmful - with harms outweighing the benefits
4. Absolute harm
Tawheed is the highest ever beneficial thing a person can have while Shirk is its baseful counterpart - the most harmful thing a person can have.
And the rest of the world either falls into category two or three.
Polygyny - a man having mutiple partners or in case of Islam, limited polygyny likely falls - fundamentally - into the second category. That with all the conditions met - polygyny could be beneficial to the person and to the society. Meaning, the devastated widow could become the second wife or the supprotless orphan could be third or the marginalized and hated prostitute could be the fourth.
In anycase marriage, whether the first, second, third or fourth can only fall into these five basic rulings in Islam:
1. It is Obligatory to those who can afford and fear of commiting fornication/adultery
2. It recommended to those who can afford but not fear of commiting fornication/adultery
3. It is Mubah/Allowed according to the opinion of some scholars (some scholars say that Marriage is Obligatory)
4. It is Detestable if Harms outweighs benefits but not leading into greater sins. If for example a man wants to get married and have another family at the expense of DESTROYING his first family that he had laborly taken care of most of his life is unreasonable.
5. It is Haram if it leads to greater Sin (like marrying one's sister and many things)
When a man and a woman decide to get married, these things should be taken into consideration.
So Yes. A woman is better off a second wife than to be a lonely, needy spinster or an abused prostitute.
Personally, If the groom meets my condition (Mujtahid and Mujahid) I can give my daughter in marriage with him even if she is the second wife - with her loving permission of course. THere is nothing undignified or less honorable in being a second wife. Aisha, the mother of the Believers was the third wife of the Prophet. But history doesnt remember her as the THIRD wife. History remembers her as the first Woman Islamic Scholar.
