I come to you when there's no one around
but I can haunt you even when there's everyone around
If you are happy, I can't touch you
If you are sad, I can break you

You shun me, you curse me
you break away from me
go to the movies or get friends together
or go out on a hike and say I don't bother

But I would come back
when there's no one around
and I can even haunt
when there;s everyone around

A friend or a foe
Tell me where i belong
i bring in tears
and memories of days bygone

When someone comes along
from you I move away
Stay at a distance
and wait to get in the way

For i come only
when there's no one around
but I can haunt you
when there's everyone around

unless you stay with someone
you can't stay away from me
unless you like your own company
you can't hide from me

Who am I?