Verse:
Em                                     C
Your love is the strongest thing I know

I reckon it's been doing weights
G
Eating raw eggs and cereal
    D   
And running ten miles a day

Em
And your love has a driving ban
                     C
From tryin' to steer intoxicated with another love inside your hands
                   G
And your love is a friend of mine
                       D
So I'll take good care tonight

Pre-chorus:
Em
If you could only say the words 

I'll take em and I'll write em down
C
And hold it deep inside of me

Until the day you found me out
G 
But I know your love
D
That's why

Chorus:

  Em
I can be your diary
            C
Baby if you open me up
        G
Keep it inside me
                  D
I'll give you the world, just give me the words (x2)

Verse:
Em                                     
And your love, has never been my enemy
C
It used to hold me and promise it would never leave
G (one strum)
Never been better since all the therapy
    D   
To read the words between the lines and take away my melody
Em            C
And your love told me it was fallin' through a different page
G                
And you know if I let you go
D
I'll still keep you safe

Pre-chorus:
Em
If you could only say the words 

I'll take em and I'll write em down
C
And hold it deep inside of me

Until the day you found me out
G 
But I know your love
D
That's why

Chorus:

  Em
I can be your diary
            C
Baby if you open me up
        G
Keep it inside me
                  D
I'll give you the world, just give me the words (x2)

Verse:
Em
You are the one I fall asleep with

But never wake up to
C
Cos work is something you must do
                           G
I trust you like you trust me

This must be true love
   D
It does exactly what it says on the tin, let me begin
            Em
You are the one I watch the movies with
                            C
And recognising my love for Keira Knightley for what it truly is
                    G
It's just an excuse so I don't have to watch Love Actually again
                                      D
But we're actually the same it's just despite me
           Em
And we eat ice cream with fishes in it

Until the dishes finish
C
Play computer games although I know I'll never win it
                G
I tried to make tea once for you in bed
                  D
But all I did was spill it so you made it for me instead
Em                                        C
Let me in bed if you get in ahead me it's better to do

Yeah love is a hell of a truth
       G
And in love we are better in two

I've been a newcomer
D
So I can never see the devil in you

Chorus:
Em
Diary
            C
Baby if you open me up
        G
Keep it inside me
                  D
I'll give you the world, just give me the words, hey


That's it, pretty basic song. You can move the capo around to suit your voice, 
capo on 5 works well. Enjoy!