why some people have become friends, lovers, couples, is perhaps the other ones have what they r persuing:

acompanying, characteristics they don't have but they wish to have, characteristics they r proud/shame of and they share the same, or sth similar as those who had left trace in their heart...

 

maybe those have satisfied the most important few items have been the most important to us. 

but what would u do if they r looking for sth the ex-beloved ones possessed from u?