This is DEFINETLY not how they play it, but I think it's close! 

G , Cadd9 

Na na na na na na na
 Na na na na na na 
Na na na na na na na
 Na na na na na na 

(hammer on) Em , Cadd9

Hey girl watcha say
 Why you pushin' me away
 Wishin' we were closer
 But we're not
 Do you want me to go away now
 Or to stay
 You can't have it both ways
 You're like a rollercoaster
 'Cause you're up
 Then you're down

           D
Can't you see?
  Em
I'm all in and
Cadd9               D
It's just not like me
 
To want you, want you
 
G , Cadd9 , G , D 

Want you to love me
 Like it's our last day, baby
 Love me like it's our last day, girl
 Want you to love me like it's our last day, baby
 Love me like it's the end
 Love me like it's the end of the world

(And then the whole thing repeats again)
 
Na na na na na na na
 Na na na na na na 
Na na na na na na na
 Na na na na na na
 
Hey, girl
 What's it take
 To get your heart
 Before mine breaks
 I've been giving my all
 Don't leave me on
 To let me fall
 
Can't you see?
 I'm all in
 It's just not like me
 
To want you, want you
 Want you to love me
 Like it's our last day, baby
 Love me like it's our last day, girl
 Want you to love me like it's our last day, baby
 Love me like it's the end
 Love me like it's the end of the world

(still figuring out the bridge, will post soon) 
Like it's the end of the world
 End of the world
 
We can't afford to fake it
 This is our time to make it
 Like it's our last few seconds
 Why can't you give us a chance?
 
Want you to love me
 Like it's our last day, baby
 Love me like it's our last day, girl
 Want you to love me like it's our last day, baby
 Love me like it's the end
 Love me like it's the end
 
Want you to love me
 Like it's our last day, baby
 Love me like it's our last day, girl
 Want you to love me like it's our last day, baby
 Love me like it's the end
 Love me like it's the end
 Love me like it's the end of the world
 
Na na na na na na na
 Na na na na na na 
Na na na na na na na
 Na na na na na na