Feelings of love towards people vary
Question

                What is the reason that makes the Muslim have feelings of love towards a few of the Muslims and not others?.
Praise be to Allah.The Muslim has many rights 
    over his fellow Muslim, including: 
The Right of brotherhood 
    which Allaah mentions in His Book, where He says (interpretation of the 
    meaning): “The believers are nothing else than brothers (in Islamic 
    religion)” [al-Hujuraat 49:10].  
He has the right of loyalty 
    and support which are mentioned in the verse (interpretation of the 
    meaning): “The believers, men and women, are Awliyaa’ (helpers, 
    supporters, friends, protectors) of one another” [al-Tawbah 9:71]. 
The Muslim also has the 
    right over his fellow Muslim that he should love good for him and wish for 
    happiness and guidance without any hatred, envy or resentment. 
It was narrated from Anas 
    ibn Maalik (may Allaah be pleased with him) that the Prophet (blessings and 
    peace of Allaah be upon him) said: “No one of you truly believes until he 
    loves for his brother what he loves for himself.” Narrated by al-Bukhaari 
    (13) and Muslim (45). 
On this basis, he should 
    have a certain amount of love for all Muslims, Arabs and non-Arabs, near and 
    far, white and black, which stems from the belief in Tawheed that they have 
    in common. This is love that stems from love of Allaah that is instilled in 
    the heart of every Muslim, because the one who loves a thing loves those who 
    love it too. 
Nevertheless, the fact that 
    the level of the love that one Muslim has for another may vary is nothing 
    strange, and there is nothing wrong with it according to the laws of both 
    sharee’ah and nature, for two main reasons: 
The first reason is that 
    the Muslims vary in righteousness and piety, and they are of varying degrees 
    of attitude, etiquette and chivalry. Because love basically stems from a 
    Muslim's commitment to the commands of Allaah, this love varies according to 
    the differences in righteousness from one Muslim to another. 
This is something that is 
    well known. Do you not see that the Muslim is obliged to love all the 
    Companions of the Messenger of Allaah (blessings and peace of Allaah be upon 
    him), yet at the same time he has to single out the ten who were given the 
    glad tidings of Paradise for extra love and respect, and that is only 
    because of the differences in their status before Allaah. 
The second reason is the 
    presence of other causes of love in some Muslims and not others. Love is not 
    restricted to one reason only, which is adherence to obedience to Allaah; 
    rather it has many other causes, including compatibility between the hearts 
    of those who love one another and spiritual harmony between them. Kindness 
    and favours are among the most important causes of creating love, and good 
    character and appearance are also important motives of love.  
If all of these causes or 
    some of them are combined in one person, he will be loved greatly, and he 
    will be closer to people's hearts than anyone else. 
We will quote here some 
    useful words by the great scholar Ibn Qayyim al-Jawziyyah (may Allaah have 
    mercy on him) in which he explains the motives and causes of love, and how 
    these very among people. He (may Allaah have mercy on him) says: 
Compatibility between souls 
    is one of the strongest causes of love. Every person is attracted towards 
    that which is compatible with him, and this compatibility is of two types: 
    original compatibility which is ingrained in the essence and that which 
    comes later because of because of living together or having something in 
    common. 
If your aims match his 
    aims, there will be harmony between your soul and his, but if the aims are 
    different, then harmony will no longer exist. 
As for original 
    compatibility, it is a kind of similarity in attitude and similarity of 
    souls. Each soul longs for other souls that are similar to it, because what 
    is similar to something is naturally attracted to it, so the two souls may 
    be similar in original creation, thus there will be a natural attraction to 
    one another. 
This is what made some 
    people say that love is not only caused by physical beauty, and the lack of 
    physical beauty does not mean that there can be no love; rather it is 
    similarity between souls and similarity in their characteristics which are 
    created in them that matter. 
The reality of love is that 
    it is like a mirror in which the lover sees his characteristics and kindness 
    in the image of the one he loves, so in reality he loves nothing but himself 
    and his characteristics and the one who has similar characteristics. 
Hence noble, pure and 
    sublime souls love the characteristics of perfection in particular, so the 
    dearest things to them are knowledge, bravery, dignity, generosity, 
    kindness, patience and steadfastness, because these characteristics are 
    compatible with the essence of these souls, unlike base and mean souls, 
    which are far away from loving these characteristics. Many people are 
    motivated to be generous and kind because of their extreme love for these 
    characteristics and the pleasure they find in doing these things, to such an 
    extent that al-Ma’moon said: Forgiveness was made so dear to me that I am 
    afraid that I will not be rewarded for it. And it was said to Imam Ahmad ibn 
    Hanbal (may Allaah have mercy on him): Did you acquire this knowledge for 
    the sake of Allaah? He said: To do something for the sake of Allaah is very 
    rare, but it was something made dear to me, so I did it. Someone else said: 
    I rejoice in giving and enjoy it far more than the one who takes from me 
    rejoices in what he takes. 
With regard to the lovers 
    of knowledge, their love for knowledge is greater than the love of anyone 
    else or anything else. Many of them will not be distracted from it by the 
    most beautiful of human images. 
Our Shaykh – meaning Ibn 
    Taymiyah – told me: I felt sick and the doctor said to me: Your reading and 
    discussing issues of knowledge is making your sickness worse. I said to him: 
    I cannot stay away from that, and I shall discuss the issue on the basis of 
    your (medical) knowledge. Is it not the case that when the soul feels joy, 
    this gives strength to the body and wards off disease? He said yes. I said: 
    Then my soul feels happy with knowledge and thus my body becomes stronger 
    and this helps me to recover. He said: This is not part of our treatment, or 
    words to that effect 
If the love relationship is 
    based on similarity and harmony, then it will be reinforced and become 
    stronger, and nothing could remove it except something stronger than the 
    cause of it, and if it is not based on similarity and harmony, then it is no 
    more than love for a reason, which will disappear when the reason 
    disappears. 
Imam Ahmad ibn Hanbal (may 
    Allaah have mercy on him) narrated in his Musnad the hadeeth of 
    ‘Aa’ishah (may Allaah be pleased with her): A woman used to go to Quraysh 
    and make them laugh. She came to Madeenah and stayed with a woman who also 
    made people laugh. The Prophet (blessings and peace of Allaah be upon him) 
    said: With whom is So and so staying? She said: With So and so, who makes 
    people laugh. He said: “Souls are like conscripted soldiers; those whom they 
    recognize, they get along with, and those whom they do not recognize, they 
    will not get along with.” The original version of this hadeeth is in al-Saheeh. 
If you look at creation, 
    you will hardly find any two people who love one another except that there 
    is some similarity between them or they have something in common with regard 
    to deeds, characteristics or goals. If the goals, characteristics, deeds or 
    ways differ, there can only be aversion and distance between their hearts. 
    It is sufficient to note the saheeh hadeeth from the Messenger of Allaah 
    (blessings and peace of Allaah be upon him): ““The believers, in their 
    mutual mercy, love and compassion, are like a (single) body; if one part of 
    it feels pain, the rest of the body will join it in staying awake and 
    suffering fever.”
End quote. 
Rawdat al-Muhibbeen, 
    66-74 
And Allaah knows best.