My first tab post but most certainly not my first time figuring out a song by ear.  I
this fun and relatively easy. I hope this works for you guys... it works for me.  The key 
may be wrong, though.  I tried to fit it as best as I could.

cm          fm      GOnce (320003@1)upon a time I thought
cm          fm          G"What's (320003@1)the one thing I haven't got?"
cm                                                  fm
There's not a single thing in this world I couldn't buy
fm                        GThat's (320003@1)when a gentleman caught my eye
cm      fm            GOnce (320003@1)or twice we went around
cm           fm           GBut (320003@1)now I'll tell you the thing I've found
cm                                     fm
You shouldn't make your move until you know the price
        fm               cm
Because gentlemen aren't nice

cm                      D (xx0232@1)dm          CJust (x32010@1)because I won't agree to take his arm
cm      B(flat)    b(flat)m   cm
And I occasionally forget his name
cm                 D (xx0232@1)           dm       CHe (x32010@1)likes to call inclemency what I call charm
cm
But I know they're all the same
             cm           fm    GI (320003@1)think I've realized my first mistake
cm       fm             GWhen (320003@1)he cried that his heart would break
cm                                           fm
I would have thought that I was worth the sacrifice
                     cm
But gentlemen aren't nice

instrumental thing.  Play whatever or find the real notes.  I don't have time, sorry.  I 
use the chords in the key of c minor here for the bass and play notes within the key.  
I think she shifts keys.

cm                       D (xx0232@1)   dm       CJust (x32010@1)because I leave him all alone for days
cm        B(flat)        b(flat)m  cm
And go about with others of his kind
cm                D (xx0232@1)      dm    CHe (x32010@1)dares complain about my evil ways
cm                        fm
And drive me out of my -- out of my mind
   cm             fm
What I relate is hard to bear
cm                       fm       GI (320003@1)only endure it so that I might spare you ladies
cm                   fm
I'm not known for my good advice
    cm
But gentlemen aren't
G (320003@1) fm
So agreeable
cm            G (320003@1)  fm
Love ain't a paradise
cm                         G (320003@1)            fm           
And if I told you once, I won't tell you twice
fm    G (320003@1)        cm
Gentlemen aren't nice
cm               cm
Gentlemen aren't nice