Her husband wants to divorce her to marry another wife
22-7-2014 | IslamWeb
Question:
Assalamulaikum. I've a wonderful marriage with my husband, we have a son and i'm also pregnant now. One day, he revealed that he has an intention of marrying a girl. I was devastated. After thinking much, he said he couldn't keep 2 wives, and have to leave me when it's time to marry her. He said he didnt really want to leave me as he loves me a lot, but he has no choice but he can't keep us both. He said that girl is not as beautiful as me and religious knowledge is also not as good as me. So i asked him why choose her over me? He said he is pleased with me and loves me very much but he still feels emptiness and discontentment. He can't figure out what causes these feelings. But his heart leans towards moving on with this girl. I've given him many religious advice and ask him to fear Allah in all matters. I'm very hurt and suffering emotionally now even though we are still in good terms, we still show affection and are intimate with each other. I'm very devastated to what makes him feel this way when there is nothing wrong at all in our marriage. For Allah's sake I try to think well of my husband but can't stop wondering is he doing the right thing? What should I supplicate to Allah? Should I pray that he would change his mind from marrying this girl? I even thought whether he is under a spell, because we love each other a lot, he is still attracted to me, we didn't argue, but he still wants to leave me when it's time to marry her. But he prays regularly. What should I do, what should I supplicate to Allah? I cry everytime thinking of him marrying her one day if Allah wills, and divorcing me. What has caused him to be like this if there is nothing wrong in our marriage? Thank you so much, I don't want to consult friend or family as I want a neutral perspective, and not receive advice that are on my side or on my favour.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Your husband has wronged you by telling you of his intention to divorce you in order to take another wife in such an unbecoming manner. Verily, such a thing hurts the woman’s feelings and causes her to be mentally distressed for no expected benefit. On the contrary, it brings about absolute evil and harm.
There is no problem in supplicating Allaah to make your husband keep you as his wife and change his mind about marrying that woman. There is no specific supplication for that purpose. You may simply supplicate Allaah with your own words (that are within your ability). This includes the supplications that are recited at times of sorrow and grief in general. For instance, Abu Bakrah 
narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: “The supplication to be said by a person afflicted with grief and distress is, ‘Allaahumma rahmataka arju fala takilni ila nafsi tarfata ‘ayn, wa aslih li sha’ni kullah, la ilaaha illaa ant (which means: O Living, O Sustainer of all existence ! In Your Mercy I seek relief; rectify for me all of my affairs and do not leave me to myself, even for the blink of an eye. None is worthy of worship but You).'” [Abu Daawood, An-Nasaa’i and Ibn Hibbaan - Ibn Hibbaan: Saheeh (sound) - Al-Albaani: Hasan (good)]
Moreover, Anas ibn Maalik reported that the Prophet, sallallaahu ‘alayhi wa sallam, said to his daughter Faatimah 
: ‘What prevents you from listening to my advice to you? Say on the onset of every morning and evening, “Ya hayyu ya qayyoom, bi-rahmatika astagheeth, aslih li sha’ni kulah wa laa takilni ilaa nafsi tarfata ‘ayn (which means: O Living, O Sustainer! In Your Mercy I seek relief; rectify for me all of my affairs and do not leave me to myself, even for the blink of an eye. None is worthy of worship but You).” [An-Nasaa’i in Al-Sunan Al-Kubra, Al-Bazzaar and Al-Haakim who said: This is an Saheeh Hadeeth that is in compliance with the criteria for a sound Hadeeth set by Al-Bukhari and Muslim] Also, Al-Albaani classified it as Saheeh in his book As-Silsilah As-Saheehah.
On the other hand, if you thought that it is most likely that your husband has been affected by a magic spell, you may ask him to recite the Ruqyah or look for someone to recite it over him. Please refer to Fataawa 88660and 82918 about Ruqyah.
Lastly, we would like to highlight two points:
First, divorce is disliked if done without need. Some scholars even deemed it forbidden and asserted that in principle divorce is forbidden without a need for it. Please refer to Fatwa 87786 and divorced their wives">104995.
Second, polygyny is permissible in Islam for men who can observe justice in their relationships with their wives. In fact, polygyny is full of many benefits in this worldly life and the Hereafter. For further information, please, refer to Fataawa 90132 and 86818.
Allaah Knows best.