G:     32003x
Dsus4: xx0233
Em:    022000

If you're NOT plauing the riff i.e. strumming:
Cadd9: x32033 (will replace Csus2!)
G:     320033
D:     xx0232 (can replace Dsus4)
Em7:   022033 (can replace Em)

E|-----|

Riff too difficult? You can play this INSTEAD of the riff:
D = downstrum
m = mute (NOT palm-mute)
Cadd9   G       D       Em7
D D m   D D m   D D m   D D m
1 & 2 & 3 & 4 & 1 & 2 & 3 & 4 &

[Guitar riff]
           hit (body)           mute        
     Csus2              G                   
e|--3E|-----|xE|-----|E|-----|E|-----|E|-----|xE|-----|E|-----||
B|--3E|-----|xE|-----|E|-----|E|-----|---3-x----3E|-----||
G|--5E|-----|xE|-----|E|-----|0E|-----|0---xE|-----|-0---|
D|--5E|-----|xE|-----|E|-----|----0E|-----|xE|-----|---0-|
A|--3E|-----|xE|-----|E|-----|E|-----|E|-----|xE|-----|E|-----||
E|--xE|-----|xE|-----|E|-----|--3E|-----|--xE|-----|E|-----||
     1  &  2     &      3   &   4      &

          hit (body)            mute         
    Dsus4              Em                    
e|--3E|-----|xE|-----|E|-----|E|-----|E|-----|-xE|-----|E|-----|||
B|--3E|-----|xE|-----|E|-----|E|-----|----0-x----0E|-----|||
G|--2E|-----|xE|-----|E|-----|0E|-----|-0---xE|-----|-0---||
D|--0E|-----|xE|-----|E|-----|E|-----|2E|-----|xE|-----|---0-||
A|--xE|-----|xE|-----|E|-----|E|-----|E|-----|-xE|-----|E|-----|||
E|--xE|-----|xE|-----|E|-----|--0E|-----|---xE|-----|E|-----|||
  1  &  2     &      3    &   4      &

Alt chorus:
This is how the chorus can be played alternatively.
D = downstrum
m = mute (NOT palm-mute)
Cadd9   G       D       Em7 D
D D m   D D m   D D m   D m D m
1 & 2 & 3 & 4 & 1 & 2 & 3 & 4 &

The 'stop riff' parts marked with a * should be played like below:
Csus2   G       Dsus4
D D m   D D m   D D m   D m
1 & 2 & 3 & 4 & 1 & 2 & 3 & 4 &

Connecting passage 2, also marked with a *:
Csus2   G       Dsus4   Em  D
D D m   D D m   D D m   D m D m
1 & 2 & 3 & 4 & 1 & 2 & 3 & 4 &

[Intro] (play above riff)
Csus2 G Dsus4 Em

[Verse one] (play riff)
Csus2                    G
I remember when we broke up the first time
Dsus4                        Em
Seeing this is it, I've had enough, 'cause like
   Csus2                        G
We haven't seen each other in a month
          Dsus4              Em
When you, said you, needed space, what?

[Verse two] (play riff)
Csus2                          G
Then you come around again and say
        Dsus4                          Em
Baby, I miss you and I swear I'm gonna change
            Csus2                        G
Trust me, remember how that lasted for a day
         Dsus4                      Em
I say, I hate you, we break up, you call me, I love you

[Pre-Chorus] (play riff)
Csus2     G           Dsus4         Em
Oooh, ooh-oh-oh-oh we called it off again last night
    Csus     G        Dsus4         Em
But Ooh, ooh-oh-oh-oh this time I'm telling you, I'm telling you

[Chorus] (play riff or play chords according to 'alt chorus')
* = do NOT play when playing riff, C  play when playing chords
Csus2  G             Dsus4     Em     D*
We are never ever ever getting back together
Csus2  G             Dsus4     Em     D*
We are never ever ever getting back together
Csus2          G
You go talk to your friends talk
   Dsus4               Em D*
To my friends talk to me
(stop riff)*
    Csus2  G                 Dsus4
But we are never ever ever ever getting back together

[Connecting passage]
(play riff)
Csus4 G     Dsus4     Em
        Like      ever...

[Verse three] (play riff)
    Csus4                         G
I'm really gonna miss you picking fights
        Dsus4                            Em
And me, falling for a screaming that I'm right
              Csus2                            G              
And you, will hide away and find your piece of mind with some
Dsus4                    Em
Indie record that's much cooler than Mine

[Pre-Chorus] (play riff)
Csus2      G             Dsus4         Em
Oooh,  ooh-oh-oh-ohh you called me up again tonight
    Csus     G        Dsus4         Em
But oooh, oh-oh-oh-oh this time I'm telling you, I'm telling you

[Chorus] (play riff or play chords according to 'alt chorus')
Csus2  G            Dsus4      Em     D*
We are never ever ever getting back together
Csus2  G            Dsus4      Em     D*
We are never ever ever getting back together
Csus2          G
You go talk to your friends talk
   Dsus4              Em
To my friends talk to me (talk to me)
(stop riff)*
    Csus2  G              Dsus4
But we are never ever ever ever getting back together

[Connecting passage 2*] (play riff or play chords acoording to 'alt chorus')
Csus2     G
Oooh, ooh-oh-oh-oh (yeah)
Dsus4     Em7   D*
Oooh, ooh-oh-oh-oh oh (yeah)
Csus2     G
Oooh, ooh-oh-oh-oh (yeah)
Dsus4      Em  D*
      Ooh, ooh

[Bridge] (filter drop, play riff or... palm muting works - 8th notes, downstrums)
Csus2     G           Dsus4       Em
I used to think, that we, were forever ever ever
    Csus4     G   Dsus4      Em
And I used to say never say never
Csus2      G                           Dsus4
 Huh, he calls me up and he's like "I still love you"
            Em                 Csus2                   G
And I'm like, I'm just, I mean this is exhausting, you know
                     Dsus4 (tape stop)
We are never getting back together, like ever

NOO!

[Chorus] (play riff or play chords according to 'alt chorus')
Csus2  G            Dsus4      Em     D*
We are never ever ever getting back together
Csus2  G            Dsus4      Em     D*
We are never ever ever getting back together
Csus2          G
You go talk to your friends talk
   Dsus4              Em
To my friends talk to me
    Csus2  G              Dsus4         Em     D*
But we are never ever ever ever getting back together
Csus    G         Dsus4  Em
We, ooh-oh-oh-oh, ooh-oh-oh-oh (getting back together)
Csus2      G      Dsus4       Em     D* 
We, ooh-oh-oh-oh, oh, getting back together
Csus2          G
You go talk to your friends talk
   Dsus4              Em D*
To my friends talk to me
(stop riff)*
    Csus2  G              Dsus4
But we are never ever ever ever getting back together