I'm just a notch in your bedpost, but you're just a line in a song

An once again, it happened.
Only this time, it's with someone else.
With someone who once told me he'll be there for me.
With someone who once told me he wouldn't be such a coward.

But turns out, I was so wrong.
This someone turns out exactly like you.
Even worse cause he promised to not be like you.
He promised to not hurt me the way you did to me.

And why haven't I learnt my lesson?
Cause I always thought that he'd change his mind about me,
that maybe he'd think I'm worth it even if you don't think the same.
But I haven't been so wrong in my entire life.

Cause whatever I fought for was useless.
Instead of telling myself to "fight for what I believe in",
I'll tell myself "nothing's worth the fight" instead.

I'm hopeless.