The grass is always greener on the other side of the fence. I don't believe it is true for all people, but some go through stages of dissatisfaction with what he/she has. The key to life is wanting what you have, not having what you want. To be pleased with simple pleasures and to find happiness in the things already gained is sublime. That is not to say that one should never set goals to attain other things, but that to be truly happy, one can find pleasure in spite of lacking certain material gains. Some the happiest people in the world live in squalor but are surrounded by loving family and friends. They may not own much, but they are rich in love and affection, friendships, and relationships. Some of the most miserable on earth are the wealthiest in terms of money, but are very alone without love, true friends, or relationships they can count on and turn to in times of trouble.
I take it from your alias, tanhaa, that you're familiar with the Four Noble Truths in Buddhism which hold that all experiences are dissatisfying (dukkha) and the cause of dukkha is craving things? Without necessarily agreeing to these propositions, it does seem that having to satisfy needs and wants is built into human life. As babies, before we can feed ourselves, we have to scream and cry to get attention to our needs; as we get older we get more capable of taking care of our own needs for ourselves. So there is always a searching and striving for something. And to have that effort frustrated of course often leads to unhappiness.
Perhaps we might explain it using Maslow's Hierarchy of Needs: if you can satisfy lower order needs such as food and shelter, then there are higher order needs one feels compelled to satisfy, such as security, then relationships, then respect from others, and finally self-actualization. Each level is a bit more refined or abstract, so takes a bit more ingenuity to obtain and ensure, so there is always striving for something more. But whether Maslow's scheme is always true of people, I can't say. But it would explain why people have a hard time saying enough, and learnign to enjoy and accept what they already have.
And if it's a Buddhist answer you're looking for, it's because we perceive things with our senses that our mind tells us will be good or bad for us, and so we are motivated to act accordingly - but in the Buddhist view, this goes on indefinitely, as every desire satisfied leads to some new desire. Falling in love with someone leads to dissatisfaction with the relationship later; but it is also dissatisfying to have love unreturned. Buddhism makes it a lose-lose proposition unless you figure out how to change your attitude on things.
One thing you might consider is if we don’t love ourselves and see ourselves as being worthy of and deserving of love, we will probably always be searching for something to fill the void. Nothing can fill that void unless we recognize the above mentioned. This could also be why we might not see the love in our life when it’s there.
I do not believe that all people are like this, at least not in terms of looking for affection when they already have it.
For me, at least, what I am doing constantly is trying to improve myself -- to learn more things, to be better as a person, that kind of thing. But I do not look for love because I already have that.
I think that people must always be striving to get something we don't have (I think that's human nature). But I think that it's pretty much up to us what we strive for. So we choose if we're going to be like the person in your quote.
Rabindranath Tagore says in a song which means, "they (humans) search love for the sake of happiness, still, bliss can not be found...".
When you'll look for something restlessly and won't find it, you'll be feeling sad. On the other hand, if you get something unexpectedly without chasing it, you'll get double pleasure. One should not chase happiness, what one should do is that keep going on and doing own's works, happiness would be achieved one day if the objective remains clear, honest, and progressive. The definition of happiness is very relative. Yet, one can earn and hold on it if s/he possesses the strength of mind and true potential.
Why should one run after bliss? Modern people are too restless to have mental stability. Unstable mind can not find contentment. Where there is no contentment, there is no bliss or peace.
The complexity of human nature should not be neglected. The trend towards individual and general happiness and welfare is an obvious concern.
Call it happiness, joy or satisfaction, what is wrong in desiring it? And why should anyone not wan it. I personally cannot think of a situation in which happiness becomes undesirable.
We tend to look down upon pursuit of happiness because we fail to understand the true nature of happiness, and because of that end up being miserable because of our pursuit of happiness. There two major issues causing this confusion. First is our failure to appreciate the relationship between happiness in the short term and in long term. Second is our mistaken belief that we can get more happiness by focusing on our own well being with complete disregard for others.
Frequently, it happens that gives us happiness in short term, reduces our ability to find greater happiness in longer term. Frequently, pursuit of inappropriate happiness objectives can lead to misery in short term as well as long term.
Over emphasis our happiness in disregard of the common happiness of the society we live, is also tends to reduce our happiness. Reasoning of selfish people suffers from a logical fallacy called fallacy of composition. I this kind of faulty logic we believe what is true of a part to be true for the whole also. Thus a selfish person may may true to increase his happiness by sealing from others rather than working to earn his living by hones means. This may be true for some isolated cases. Burt when every one in the society stops working and starts stealing, there will be nothing available for stealing and the world will come to an end. This is the reason why most of the religions in the world advise us to "love thy neighbor as thyself".
It is not necesarily happiness but a fulfillment of needs according to Abraham Maslow.The following are from : A.H. Maslow, A Theory of Human Motivation, Psychological Review 50(4) (1943):370-96.
Physiological Needs These are biological needs. They consist of needs for oxygen, food, water, and a relatively constant body temperature. They are the strongest needs because if a person were deprived of all needs, the physiological ones would come first in the person's search for satisfaction.
Safety Needs When all physiological needs are satisfied and are no longer controlling thoughts and behaviors, the needs for security can become active. Adults have little awareness of their security needs except in times of emergency or periods of disorganization in the social structure (such as widespread rioting). Children often display the signs of insecurity and the need to be safe.
Needs of Love, Affection and Belongingness When the needs for safety and for physiological well-being are satisfied, the next class of needs for love, affection and belongingness can emerge. Maslow states that people seek to overcome feelings of loneliness and alienation. This involves both giving and receiving love, affection and the sense of belonging.
Needs for Esteem When the first three classes of needs are satisfied, the needs for esteem can become dominant. These involve needs for both self-esteem and for the esteem a person gets from others. Humans have a need for a stable, firmly based, high level of self-respect, and respect from others. When these needs are satisfied, the person feels self-confident and valuable as a person in the world. When these needs are frustrated, the person feels inferior, weak, helpless and worthless.
Needs for Self-Actualization When all of the foregoing needs are satisfied, then and only then are the needs for self-actualization activated. Maslow describes self-actualization as a person's need to be and do that which the person was "born to do." "A musician must make music, an artist must paint, and a poet must write." These needs make themselves felt in signs of restlessness. The person feels on edge, tense, lacking something, in short, restless. If a person is hungry, unsafe, not loved or accepted, or lacking self-esteem, it is very easy to know what the person is restless about. It is not always clear what a person wants when there is a need for self-actualization.