Hmm. Methinks he doth protest too much with that one.
Goodbye to You - Scandal
I blame this thread for putting that song in my head, so now everyone can suffer with me. 
For a serious song about a dying relationship, try “Never a Time” by Genesis
Or, for a change of pace, “Glad to See You Go” by the Ramones
“Talk to You Later” by the Tubes
The Blues is Alright – Little Milton
The Thrill is Gone – B.B. King
I Will Survive – Gloria Gaynor
You give Love a Bad Name – Bon Jovi
I’ll Be Alright Without you – Journey
I will fight back with “I am the warrior…and heart to heart you’ll win! If you survive…the warrior! Shooting at the walls of heart ache…bang bang!”
I’ve forgotten what it was in you (that put the need in me) - Maria McKee
Maybe a little too downbeat: Lover’s Cross - Jim Croce. Or indeed Next time this time.
Oh, there are lots of Jim Croce songs- but since the OP wants upbeat, go with “One Less Set of Footsteps.”
Sigh… That’s what I was gonna say.
50 Ways to Leave Your Lover, Paul Simon
20 Years of B.B. King, Curtis Salgado
“I’ve learned more about the blues in two weeks of you,
than in 20 years of BB King.”
We Just Disagree by Dave Mason.
So let’s leave it alone,
'Cause we can’t see eye to eye,
There ain’t no good guy,
There ain’t no bad guy,
There’s only you and me and we just disagree
I love that title.
The singer in this song *might *still be in love, but his girlfriend definitely isn’t…
Oh, how about Sam Kinison’s version of “Are You Lonesome Tonight”?
Forgot about a great one:
This Masquerade - Leon Russell
This Masquerade - George Benson (Ignore the really annoying amateur video.)
It doesn’t get much more upbeat than Brand New Lover by Dead or Alive.
Or if you specifically want love mentioned, there’s Da Da Da by Trio.
"Last Song for Shelby Jean by David Bromberg:
“So don’t call me anymore, you know how much I hate the phone
And don’t come to my house - I need to spend some time alone
And I know all right
How much I’ll want you at night
Good God, do you think I’m made of stone
But this is really goodbye, if you want to you can cry
But I think you’d better just go home.”
Beautiful, heartbreaking song!
Agree, and would add “Wasted Time” by the Eagles.
You’re back out on the street, and you’re tryin’ to remember
How will you start it over? You don’t know what became
You don’t care much for a stranger’s touch,
But you can’t hold your man..
You never thought you’d be alone, this far down the line
And I know what’s been on your mind
You’re afraid it’s all been wasted time
Oh, that might rule out the Eagles and Don Henley songs I mentioned earlier then, eh?
How about these not yet mentioned:
Kelly Clarkson - Since U Been Gone (a genuine classic IMHO)
Peter Bjorn & John - Let’s Call It Off (The Gotye song always reminds me of this earlier Euro-emo song)
Mojo Nixon & Skid Roper - Gonna Eat Them Words