I heard this song on the radio. Its from the late 70s or early 80s.
I think these are the 1st verse/chorus
(man)
Once in my life I have found someone to count onto.
there are so many things that become of you, oh.
(girls chorus)
shouldve seen the warning signs
(Man)
the night that I came to you
(girls chorus)
shouldve seen the warning signs
(man)
I shouldve been watching you
The guy sings pretty softly. At the end it really picks up though, almost like disco.