How can someone tell how much one is in pain..

I sometimes smile in curiosity when someone can tell how much the other one is in pain cause its not natural to,unless u knoe that person deeply..
u can say it as a traumatic bond or a bond of formality but it just happens..
its so difficult to tell how lonely one is when someone whom was urs becomes someone elses,if this is the world then why is the world like this?and if this happens why does it?
if u grab the hand ur soul gets attach will the heartbeat can be felt..
and then the saddness is shared equally..
why does someone break the thread of hope?
doesnt the pain stay for all the centuries..
people say that the bond of love is the bond of years..
life is book of questions and answers left to be asked and each question is important but when its not solved its a blank page..
a page of left memories and a blank not filled..
but the angels on our right and left hands fill in the blanks suspiciously and a page is completed..
a writer writes to express,a painter paints and a singer sings and this is how we live with our feelings..