The purpose of this life is to attain "transcend comprehension"

"ALL ARE CONCERNED ONLY WITH THEIR OWN HAPPINESS"

In this world, I have seen love to be false. Whether they are spouses or
friends, all are concerned only with their own happiness...(sggs 536).
The woman loves the man only for his wealth — so long he is earning money (sggs 951).
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The Gurbani boldly declares that in this material world "all are concerned only with their own happiness". Here the Gurbani even dares using the word "all" — spouses, children, parents, brothers and sisters, friends, and so on — because here the Gurbani is revealing us the Supreme Truth. The Truth being that which is true in the past, present and future. Please note, here the Gurbani is neither discouraging us nor scaring us away from forming worldly relationships. Instead, the Gurbani is simply making us aware of the real nature of these worldly relationships so that we are not surprised or shocked later. Our deluded consciousness (false ego-sense or Haume), however, may not agree to this Truth (specially when intoxicated with youth), but that does not change the Truth. If one does not believe it now, then that person is certainly in for a huge surprise later!

Our mind or worldly consciousness (false ego-sense or Haume) is the problem. Those who see their Self in others or see others as the extensions of their own Soul (selflessly without any greed) are very "rare" in this world. Also, as the Gurbani says, those who by becoming the Gurmukhs (egoless or unselfish beings) understand this Truth are also very "rare" in this world.
For example, let us consider the relationship of husband and wife. Man emotionally loves his wife, and vice versa. According to the Gurbani, however, "The woman loves the man only for his wealth.— so long he is earning money." If for some reason, such as chronic disease or serious sickness or old age, the husband is unable to earn money, the wife's love and attitude will dramatically shift. The same is true for the husbands also. If someone does not have this experience yet, then wait until you are sick or old and unable to earn money anymore!
According to the Gurbani, the purpose of this life is to attain "transcend comprehension".

Sooner we realize this goal, the better.

The only other option we have is more repeated pain and suffering. Not a good option! To stay steer clear of the worldly bondage while living in it, the Gurbani's advise to us is to assimilate the following examples: (1) a bird flies in the sky all day, but it never leaves any marks or footprints behind; (2) a duck swims against the stream, but does not get wet; (3) a lotus flower grows in the slimy mud and water, but remains untouched by both; and (4) a fish remains and swims in the water, but its path through the water cannot be seen. This is the state of the Gurmukh or Divine Life. It's easier said than done. But considering all or options, we do not have a better choice. During "Sidh Gost", Baabaa Nanak was asked about his "way" and his life object. His response to them was:

* Awsix bYsix iQru nwrwiexu AYsI gurmiq pwey: Aasan baisan thir naaraain aisee guramat paae: I sit in the posture of the eternal, imperishable Lord is my way. These are the Teachings I have received from the Guru-God — in other words, the attainment of such a transcend comprehension is my life object (sggs 938).
* jYsy jl mih kmlu inrwlmu murgweI nY swxy ]suriq sbid Bv swgru qrIAY nwnk nwmu vKwxy ]rhih iekWiq eyko min visAw Awsw mwih inrwso ]Agmu Agocru dyiK idKwey nwnku qw kw dwso: Jaise jal mahi kamal niraalam muragaaee nai saane. Surti sabadi bhav saagar tareeai Nanak naam vakhaane. Rahahi ekaanti eko mani vasiaa aasaa maahi niraaso. Agam agochar dekhi dikhaae Nanak taa kaa daaso: The lotus flower floats untouched upon the surface of the water, and the duck swims through the stream; with one's consciousness focused on the Divine name, one crosses over the terrifying world-ocean. O Nanak, chant the Divine Name. One who lives alone, as a hermit, enshrining the One Divine in his mind, remaining unaffected by hope in the midst of hope, sees and inspires others to see the inaccessible, unfathomable Being. Nanak is his slave (sggs 938).
* gurmuiK bUJY Awpu pCwxY scy sic smwey: Gurmukh boojhai aap pashaanai sache sach samaaye: By becoming the Gurmukh, I have come to understand and realize the Self; I have merged in the Truest of the True (sggs 938).
* ijau AwkwsY pMKIAlo Koju inriKE n jweI]ijau jl mwJY mwClo mwrgu pyKxo n jweI: Jiyu aakaasai pakheeale khoj niksiyu na jaaee. Jiyu jal maajhai maashale maarag pekhano na jaaee: As the path of a bird’s flight across the sky cannot be seen, and the path of a fish through the water cannot be seen (sggs 525).