Why do we take an interest in another human being? In almost every instance and with almost every person the reason interest is taken in another human being is because they full a NEED or a WANT of ours.
To wit:
A doctor needs his patients for his livelihood. That is why he is interested in them.
When you walk into a store and a friendly lady greets you with a cheerful "good morning, may I help you" it is because she needs to earn a living and if she doesn't do her job [which includes offering assistance] then she will lose it. Ironically, you are only interesting because of what you can do for HER.
When you go to a restaurant the waiter interests you because he will bring you dinner. The moment you have your food you want him to go away until you need him for something else.
When you have a shyla to ask the rabbi interests you because he is fulfilling a need. After the need is fulfilled he stops being interesting. Shul boards hire and fire rabbis right and left. As long as they feel that the rabbi is fulfilling their needs and wants they keep him aboard. When they feel he is no longer doing what they desire - out.
When I am at the kotel or near a shteibel and people anxiously approach me and ask if I can join their minyan it is clearly not about me. They are only looking at me because I am male and over 13. The MOMENT I say that I already davened they immediately lose interest in me.
A person will befriend someone because he fulfills a human need to have friends. If he is no longer perceived as a good friend then he will no longer be on his former friend's radar.
If a single boy sees a girl over the mechitza chuckling away and she also happens to be beautiful - he will inquire about her. He is interested. She can potentially fulfill many of his basic needs. If he finds out that she is engaged - or that he wasn't looking clearly and it was his sister, then he immediately loses interest because she is no longer marriage property.
And so on and so forth.
I am not arguing that in every example I gave there is something wrong or unethical that is transpiring. Just that most of why we are interested in other people is because somehow it relates to the quality of OUR lives and has NOTHING to do with the other person.
When a beloved spouse of 40 years passes on, it happens quite often that the widow/er will remarry a short time later. That is legitimate. But it shows that as long as the spouses filled their role, they were comitted to each other. Now that the relationship has ended he [i.e. the living one] can move on to someone else quite easily.
We human beings are naturally very self interested and self absorbed people. Almost all of our dealings with others center around a need or needs of our own. I often call people and they look at their called id and see that it is me. Sometimes they will answer, quite often, they will not [and not return the call either]. What is the explanation? It is very simple - when they see my number they subconsciously ask themselves "Can he fill a need or want of mine or not?" The need might be to have a friendly conversation, the need might be to fulfill their curiosity as to why I am calling, the need might be to show me respect and answer the phone or that they have been meaning to speak to me about something and now they will have me on the line. But if they have no compelling reason to speak to me - and maybe they don't even like me or have a want or need NOT to speak to me then they won't pick up. Truth be told, I make the same "cheshbon" at times. I see the name and do a quick scan in my mind if it is worth my time and effort to pick up. I am not proud of it and find it quite disgusting but that is the nature of the human animal. If he is calling and wants to speak with me - then what does it matter whether I want to speak to him? He wants to speak to me and morally that should obligate me to pick up the phone [or at least call the person back when I have more free time]. But the reality is that my self interest always plays a key role.
There is a higher level where someone has a need to do for others. If you have a healthy drive to give tzedaka, then you will seek out the poor person. But this is also because he fills a need of yours. This is a higher level need than what we have been discussing until now. This is not using somebody else in order to take or in order to give with the ultimate purpose of taking in mind but "using" the other person in order to give altruistically.
A doctor may seek out patients because he loves to heal just for the sake of helping people feel well and mitigating suffering. This is a higher form of giving but again, the doctors personal need to give is being fulfilled.
The Rebbi may want to teach the students Torah and have the students in mind and not be doing it for the money or prestige but to give and help others grow. But very often this is the outgrowth of the Rebbis personal need to give. A higher level of taking but also taking in a sense. The other person is a means to fulfill MY needs. I need to teach and give and this student is the canvass on which I paint my picture.
A parent gives to a child but only because it is HIS chiild and he feels a PERSONAL connection. That is why on his own child's wedding he will spend 50k but when someone asks him for money for someone else wedding he may [or may not] give him 18 dollars. What is the difference? They both need to get married so why the huge gap? The answer is that I have a NEED and WANT to provide for my own child but have no such inclinations towards other people's children. They are not MY problem, hence I am not interested in them. If I found out that the person at the door saved my life when I was seven I will then give a huge check because I found my self interest.
The lower level [with taking in mind as the ultimate goal] which characterizes most interactions is necessary [we are but human] however must be minimized in every way. Try to constantly remind yourself that this person doesn't exist for you. He has his own independent purpose in life.
Th higher level is definitely something to strive for. Namely, viewing other people as the potential receptors of your kindness. It could be a kind word, a smile, a check, a ride or any chesed for that matter. See the world as a springboard for you to fulfill your purpose as being a giver.
But their is yet a higher madreiga. G-d is on this madreiga. Give just in order to give. NOT because you have a "need" to give. Not because you are "חייב" and want to be "יוצא". Erase the "me" from the equation. It is not about you at all. It is so completely NOT about you. Every other person [or at least Jew] on earth HAS NOT LESS of a tachlis in life than you do. They are not hear just to help you fulfill your tachlis but have an independent existence. In Chasidus this is called ביטול.
It is a BEAUTIFUL [which is actually very close to the word "bittul. Bittul -Beautiful. Close] middah where the EGO IS NULLIFIED. Hashem has no ego. It is not about His needs at all because he needs nothing.
If you have reached the higher level where you seek out others to do good on their behalf and not to get anything from them in return but because you have a need to do good - then I am a great admirer of yours.
If you do good for others without your own personal satisfaction in mind at all but purely for the sake of the other - then I am your chossid and would be honored to roll around in the dust of your feet....:-)