Analysis of Expiration Date

I, have an expiration date
It's not always the same
But it always happens
If they mean anything to me...
        They leave

I'm always quickly replaced
Forgotten and disregarded
Just like garbage
Tossed away because it has no value

The moment I start to "feel"
I hear the clock start ticking
Banging away in my brain
Tearing through me like a raging bull

My heart breaks every time
Yet I never learn
Never stop hoping
This one will stay

I, have an expiration date
I'm merely a filler of time
While they search and find
Someone worthy,  of value and significance

I have an expiration date!