I love this song :) It's so cute, haha. 
This is how Tiffany plays it, so i'm for sure it's right.

Capo on 7th


Intro: G, C, D, G


Verse: G, C, D, G


Pre-chorus: Am, G, Em, D


Chorus: Em, C, G, D
OOPS: In the end of the chorus it says:
"And you, are the music to my melody
      Em                       C
And we, yes you + me, create the perfect, the perfect, chemistry"
    G                               D           Am


Bridge: I have to show you this one:
And I have, wanted just one guy, to 
    Am                      Em
show me that they aren't all the same
                     Am           Em
And you are, that one guy for me, I 
    Am                        Em
wanna feel this way forever, for eternity
                 Am                 D
And you have showed me love is true  
    Am                          Em
and no one understa-ands, me better than you do
                   G                      D

Have fun!