There’s just a bit of melody and a few words floating in my head, and 10 minutes of googling didn’t tell me what the song is.
I wouldn’t stake my life on any of the following clues being totally accurate, but…
–The song dates from 1964-1975.
–The lyrics begin with a one syllable girl’s name (Jill?), and then, “just between you and me”
–The lyrics then might go, “I hear your voice”
–The song was probably a minor Top 40 hit.
–The opening of the song is very soft, with an ambiance similar to the beginning of “One is the Loneliest Number…”