In order for the guitar to sound like the piano from the studio version, play with fingers like this:

   C                 Am                Em
e|-3---3---3---3---|-3---3---3---3---|-3---3---3---3---|-3---3---3---3---|
B|-1---------------|-1---------------|-0---------------|-----------------|
G|-0---------------|-2---------------|-0---------------|-----------------|
D|-----------------|-----------------|-----------------|-----------------|
A|-3---------------|-0---------------|-----------------|-----------------|
E|-----------------|-----------------|-0---------------|-----------------|

[Chorus]
                         C
Mmm, baby, I don't understand this
                          Am
You're changing, I can't stand it
                          Em
My heart can't take this damage
                           Em
And the way I feel, can't stand it
                         C
Mmm, baby, I don't understand this
                          Am
You're changing, I can't stand it
                          Em
My heart can't take this damage
                           Em
And the way I feel, can't stand it
                         C
Mmm, baby, I don't understand it

[Bridge]
                                  Am
Girl, you're making it hard for me
                                  Em
Girl, you're making it hard for me
                                  Em
Girl, you're making it hard for me, uh

C                                   Am
  Girl, you're making it hard for me
                                  Em
Girl, you're making it hard for me
                                  Em
Girl, you're making it hard for me

[Chorus]
                         C
Mmm, baby, I don't understand this
                          Am
You're changing, I can't stand it
                          Em
My heart can't take this damage
                           Em
And the way I feel, can't stand it
                         C
Mmm, baby, I don't understand this
                          Am
You're changing, I can't stand it
                          Em
My heart can't take this damage
                           Em
And the way I feel, can't stand it
                         C
Mmm, baby, I don't understand this
                          Am
You're changing, I can't stand it
                          Em
My heart can't take this damage
                           Em
And the way I feel, can't stand it
                        N.C.
Mmm, baby, I don't understand it