I have found a German word that seems to describe the feeling of longing that we have and that I am referring to perfectly - Sehnsucht.
You may listen to how this word is pronounced here - http://www.pronounceitright.com/pronounce/11402/sehnsucht
According to oxforddictionaries.com, sehnsucht is yearning; wistful longing. However, there is much much more to be said about this word in many psychology journals. Here http://psycnet.apa.org/journals/dev/43/3/778.html, the Developmental Psychology journal goes in depth about the term.
Additionally, there are plays and movies on the subject. Hope to find some of those and read/watch them.
I am currently reading more about this and plan to contact some psychologists on the subject.
Stay tuned... more to come on Sehnsucht later!