I wish I had the natural talent or training to play by 'ear' ... I admire musicians who can hear where the chord changes are going ... Obviously, except for a ton of songs I've memorized, I play with music, mostly lead sheets with lyrics, lyrics with chords over them, or fake books ... I make up my own 'book' of tunes I play by making copies from the books I purchase ... I have found that using the arranger kb (kn6000) my ear is getting better, especially if playing along with a midi file ... but I'm not going to be doing any 'open mike nites' anytime soon ...
t.
PS A lifetime ago when I was teaching accordion, an adult came to the studio saying he wanted to learn how to play by reading music ... After a few weeks, I felt he was still relying on his ear, even though he denied it ... So I wrote out something like "Mary had a little lamb" but titled it "Popeye the sailor man" ... sure enough one week later the student gave me a great rendition of "Popeye" ...
t.