I Don’t Know Why (I Just Do) by Frank Sinatra is in Eb at 76 beats per minute and runs 2:19 across 25 bars. It uses 20 chords — Bb, Eb9, C9, Cm7, F7, Bb6, Cm6, C#dim7, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? I Don’t Know Why (I Just Do) guitar melody tab.