Here is the Doc Dogg patented break up:
1. Tell her you are bored in bed and want to try things that will make a pornstar blush. (hehe, use caution though, I miss judged a girl and ended up trying new and wonderful things for the next 12 months with her

)
2. Tell her you think it is about time she let you date other girls during the times she is not around, like through the week. I like to call it "Time-sharing"
3. Start chatting up her sisters, cousins and friends. Do this infront of her and act like it is her fault for driving you into the arms of another women. Sleep with them too, if you have the skills to get them in bed.
4. Start to act like the biggest girlie-man around. Make up stories about how the new office girl is pushing you around or something and constantly whine about it at every waking minute of the day.
I've only had one girl stick around past no. 4, but she was seriously in love with me and turned into a freak when things turned bad (I think she even stole my dirty underwear near the end. I know she still keeps a dirty old shirt of mine under her pillow)
5. Tell her that she makes you seriously unhappy and that there is no way that you can continue to be with her. You have tried to let her down easy, but she is just not getting the hint so you have to make a stand. Put all of her stuff in a box, delete her number from your phone in front of her and tell her she has to go and not come back. If she tries to contact you, ignore her until she gets over you and stops calling.
Edit: removed all the censored words (can't help swearing, I am australian after all)