Try

I fell in love with the idea of you. 

The thought of you was too tempting to resist 

The man of my dreams?

I wouldn't go so far as that

Try: the man who I adapted my dreams to

I fell in love with your friendship 

Blissful and ignorant and cared for

      That was me

      And that was good 

Try: perhaps everything I wanted but was not really sure either way

Warm fuzzies flooded my heart 

When you were near 

      I'm just a cold person 

      With a sadly broken heart

I fell in love with the idea of you

Which you've now left behind 

Try: the man I thought I needed

But that's okay

I have the part of you I love

You just sit there and grin your stupid grin

Try: the idea of you was too good to be true