He regrets his first marriage and wants to take a second wife
Question

                I have been married for a year and a half, but I do not find in my wife anything to keep me chaste, because she is not beautiful and I regretted marrying her, which made me think about taking another wife, although my wife loves me and is good. But my problem is that I look at women with the aim of marriage, but when I mention the idea of a second marriage to my wife, she says that she could not live with me if there was another wife. 

What should I do? I do not want to divorce her.
Praise be to Allah.Firstly: 
Your real 
    problem is what you mentioned about looking at women, even if that is with 
    the aim of marriage, as you say. Whoever looks at women spoils his religious 
    commitment and weakens his faith, and he no longer appreciates his wife and 
    he spends all his time thinking another woman. This, of course, puts him off 
    his wife even more and makes him think more of a second marriage, which he 
    thinks is the way out. Whoever is aware of how people are will realize that 
    because of this haraam looking, what was beautiful yesterday becomes ugly to 
    them today, and as time passes, what was new becomes old and boring, so they 
    will live a restless life and will never settle down, and one wife or two 
    wives will never be for them. 
Hence we 
    say: Fear Allaah, may He be exalted, and lower your gaze and avoid looking 
    at that which Allaah has forbidden. Go back to your wife and think about 
    some of her attractive features and her good qualities, and you will find a 
    lot of goodness, as the Prophet  (peace and blessings of Allaah be upon 
    him) said: “No believing man should hate a believing woman. If he dislikes 
    one of her qualities, he will be pleased with another.” Narrated by Muslim 
    (2672).
 If a person 
    wants to get married, it is not permissible for him to look at every woman 
    who is coming and going, rather it is permissible for him to look at the one 
    to whom he wants to propose marriage when he has decided to propose. So if 
    he is told about a woman and he is pleased with her religious commitment, 
    character and family, then all that remains is for him to look at her. It is 
    permissible for him to do that whether it is with or without her knowledge, 
    a look without desire. 
As for what 
    some people do, looking freely at women right and left, on the grounds that 
    they will choose one of them, this is haraam and is not approved of in 
    sharee’ah or accepted by sound human nature; no one would accept this for 
    himself or his family. 
We think 
    that you understand all of that, and that deep down you understand that 
    choosing a second wife by looking at women who are coming and going, is 
    nothing but a trick by means of which the shaytaan has fooled you into 
    haraam looking which will only make you more restless, in addition to it 
    being disobedience towards the Most Merciful, may He be exalted, and 
    obedience to the Shaytaan and falling into his trap. 
Secondly: 
It is 
    permissible for a man to marry one or two wives, up to four, if he is able 
    for that both financially and physically, and he thinks that he will be able 
    to treat his wives fairly. 
It is not 
    essential for him to have the first wife’s permission in order to take a 
    second wife. Most women would not agree to plural marriage and they think 
    that it is impossible to live with it.  This is due to many reasons, 
    including the biased media which regards plural marriage as a crime and an 
    action that will make the first wife feel that there is something wrong with 
    her; in many cases men also abuse this right and tend to be unjust and 
    transgress the limits, except for those whom Allaah protects. 
The wise man 
    must look at his family and how prepared they are to accept a plural 
    marriage; he must weigh up the settled life that he has now and what may 
    happen in the future, and think thoroughly – without emotion – about whether 
    he needs a second wife, and how able he is to take care of two households 
    and two families. He has to pray to Allaah for guidance (istikhaarah) before 
    making any move towards marriage, and he has to make a good choice, so that 
    he will not feel regret again and realize, when it is too late, that he is 
    seeking something unattainable, no matter what type of woman he marries. 
If he 
    decides that he wants to take a second wife and his circumstances would 
    allow for that, as we have mentioned above, and he is serious about it, then 
    and only then is it permissible for him to look at the woman to whom he 
    wants to propose marriage. 
But at this 
    point we would like to point out a mistake that many a husband makes, when 
    his life and that of his family is disturbed when this issue comes up from 
    time to time. What is the point of bringing up this issue that causes 
    problems – do you want to make her miserable for the rest of her life? 
If you are 
    serious – and we think that it is too early for you to be serious about it 
    because you have only been married for a short time – then put your trust in 
    Allaah and you will be able to deal with matters as they arise.   
May Allaah 
    help us all to do that which He loves and which pleases Him. 
And Allaah 
    knows best.