The album you're referring to is "The Diamond Mountain Sessions" (2001) by "Sharon Shannon and Friends." One cut is called "Say You Love Me" and the "friend" involved is Dessie O'Halloran, who sings lead vocal.

I've listened to a sound sample, and as far as I can tell, it's the same as an old bluegrass song called "I've Waited As Long As I Can" by Hylo Brown, and originally recorded by Hylo Brown and the Timberliners in 1959.

Nevertheless, it's an interesting arrangement. You've got Irish musicians playing a bluegrass song in a Cajun style!

Lyrics copied from http://www.musicpotential.com/SONGS/BLUEGRASS%20SONGS/Bluegrass%20Songs%20(I)#anchor3397491

I'VE WAITED AS LONG AS I CAN
(Hylo Brown)

I've waited for you and I've always been true,
But this waiting no longer I can stand.
I know you've had time, dear, to make up your mind.
I've waited as long as I can.

CHORUS: I've waited to hear you say you love me,
And longed for the day you'd take my hand.
I asked again last night for your love so divine.
I've waited as long as I can.

Done all I can do; said all I can say.
Oh, why can't I make you understand?
I've wanted you for mine but I've wasted my time.
I've waited as long as I can. CHORUS

Now I'll jut say goodbye. The tears fall from my eyes,
For you have made it plain that I can't win.
No one will ever know the pain that I've been through.
I've waited as long as I can. CHORUS