Relationships

I have been thinking about relationships for sometime..
Sometimes I wonder what is the most important ingredient that goes on to make a relationship strong.. Is it love..trust..mutual respect..care.. the need to keep a relationship going.. selflessness..friendship..commitment.. What is it that makes a relationship strong and everlasting?
Sometimes i feel all of the above are necessary but if i needed to pick one which one would it be?
Can a relationship be truly selfless.. totally giving and not have any expectations in return?
Can you trust a relationship so much that u give a damn to the rest of the world?
What would happen if that relationship would then betray you? What would you do in such a situation.. heartbroken do you go looking for another relationship that would fill that void in you.. or live with the pain for the rest of your life and not trust any further relationships that you may get into?
Why does one strive for a relationship going knowing it has a lot many faults.. knowing that sometimes you lose your identity in them..
Sometimes you are a mother.. a daughter.. a friend.. a girlfriend.. a wife..
How many such identities can we balance.. Giving importance to one you are blamed of ignoring the others.. How long can one go balancing these relationships and losing out on the relationship you have with your soul?There is always a conflict which never ends..
So many questions.. So many if's and but's but the answer's vary..
Which is the best option to pick.
Life always makes you chose things.. and you choose whats best for you at that point in time .. But then again you are not sure if that choice was the right one..Things can go wrong anytime anywhere..
Life is such a complicated thing.. in such situations how do you keep yourself happy?
makes others around you happy?
we can't make everyone happy but still we strive to do that knowing its a next to impossible task.. So now if you know its so then why do it? is that right?But if you stop then whatever chances you have to make people happy goes away.. Its a cycle and how does one ever get out of it!!! Beats me.. anyone with asnwers????