These funny lines can be used to end a relationship instead of starting one.

"Our relationship is like a fat guy."
"What?"
"It's not working out."
"You're not Mr. Right.... just Mr. Right Now."
"Hey babe, you heard of the movie 'Other people?'"
"Yeah, why?"
"I think we should see it."
Roses are red violets are blue sugar is sweet and so were you... but now the roses are wilted the violets are dead the sugar bowls empty and so is your head.
"I treated this relationship like my diet, one cheat day a week."
"This isn't easy and neither are you. I'm breaking up with you."
"Sorry I stopped contacting you. I had to go back to rehab."
"Maybe this is not the right time for us"
"My cat doesn't like you."
"It's not you...it's your taste in music"
Girl: Want to see a magic trick?
Boyfriend: Sure.
Girl: Poof you're single.
"Roses are red, Violets are blue. Garbage is dumped, now so are you."
"I'll always remember last night, but I think we can forget about tomorrow."
"Really, our time together has just become more effort than you're worth."
My d**k is committed to you, but my heart is not.
"Remember when I asked you out? Well, I was talking to the girl behind you"
"I just can't take the bad lovemaking anymore".
"Do you believe in love at first sight? How about misery after three years?"
"You deserve better and so do I."
"There's something I've been wanting to say since the day we met - goodbye."
"Roses are red, violets are blue. We're breaking up beacause I never loved you."
"I just can't live with the pathetic tickles that you call thrusts anymore."
"We are like a broken mirror. It is better to leave it broken than hurt yourself to fix it."
Boy: Want to hear a joke?
Girlfriend: Sure.
Boy: Our relationship.
"You're perfect in every way, just not for me."
"I now pronounce you dumped and single. You may now kiss my ass."
"Hey baby, are you being followed? Because I've been seeing people behind your back."
"The longer we are together, the less serious I am about you."
Knock knock. Who's there?
You're.
You're who?
You're single again.
"Look, our relationship is like doing push ups on your knees. It's just not working out"