How?

How do they walk away
Acting as though that was a dream,
A dream never dreamt.
Leaving behind a mark,
An embedded image in your brain.
Like a scab that will heal in time,
Leaving only the small reminder of those days.
Before long they could be a passerby unaware you exist.
All those season's missed,
milestones passed.
Nothing more then a dream you never dreamt at all.