电梯机房电源箱新标准:Ain't nothin' but a heartache

I Want It That Way (Max Martin/Andreas Carlsson)
Yeah
You are
my fire
The one
desire
Believe
when I say
I want it that way
But we
are two worlds apart
Can't reach to
your heart
When you say
I want it that way
Tell me why
(Ain't nothin' but a heartache)
Tell me why
(Ain't nothin' but a mistake)
(Tell me why)
I never wanna hear you say
I want it that way
Am I
your fire
Your one
desire
Guess I know
it's too late
But I want it that way
Tell me why
(Ain't nothin' but a heartache)
Tell me why
(Ain't nothin' but a mistake)
(Tell me why)
I never wanna hear you say
I want it that way
Now I can see that we've fallen apart
From the way that it used to be, yeah
No matter the distance
I want you to know
that Deep down inside of me
You are
my fire
The one
desire
(You are, you are, you are, you are)
Don't wanna hear you say, hey
Ain't nothin' but a heartache (hey, heh, yeah)
Ain't nothin' but a mistake (don't wanna hear you say)
I never wanna hear you say (oh yeah)
I want it that way
Tell me why
(Ain't nothin' but a heartache)
Tell me why
(Ain't nothin' but a mistake)
(Tell me why)
I never wanna hear you say
(Don't wanna hear you say)
I want it that way
Tell me why
(Ain't nothin' but a heartache)
(Ain't nothin' but a mistake)
Tell me why I never wanna hear you say (hear you say, yeah)
I want it that way
Cause I want it that way

中的Ain't nothin' but a heartache
什么意思?Ain't nothin'怎么理解?