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

Girl: Your ex is so attractive
Boy: Which one?
Girl: ME. Goodbye.
Knock knock. Who's there?
You're who?
You're single again.
Boy: Want to hear a joke?
Girlfriend: Sure.
Boy: Our relationship.
Girl: Want to see a magic trick?
Boyfriend: Sure.
Girl: Poof you're single.
"Our relationship is like a fat guy."
"It's not working out."
"Remember when I asked you out? Well, I was talking to the girl behind you"
"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 treated this relationship like my diet, one cheat day a week."
"The longer we are together, the less serious I am about you."
"It's not because I don't like you, it's because I hate you."
"If it's meant to be it's meant to be....but just to be clear it isn't."
"Look, our relationship is like doing push ups on your knees. It's just not working out"
"We are like a broken mirror. It is better to leave it broken than hurt yourself to fix it."
"My cat doesn't like you."
"This isn't easy and neither are you. I'm breaking up with you."
"I took a gamble and chose you, now i believe I made a bad bet."
"Hey babe, you heard of the movie 'Other people?'"
"Yeah, why?"
"I think we should see it."
"You deserve better and so do I."
My d**k is committed to you, but my heart is not.
"Sorry I stopped contacting you. I had to go back to rehab."
"I just can't live with the pathetic tickles that you call thrusts anymore."
"You're not Mr. Right.... just Mr. Right Now."
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 wish I could say you were the most special person in the world, but you're not."
"Really, our time together has just become more effort than you're worth."
"Maybe this is not the right time for us"
"Hey baby, are you being followed? Because I've been seeing people behind your back."
"It's not's your taste in music"
"You're perfect in every way, just not for me."