Before we get started on getting rid of a girlfriend, you have to understand one thing: every last person on earth is completely ignorant when it comes to understanding the relationship you have with this woman. It's not that they don't know what they're talking about...but, really, they don't know what they're talking about. Give them a little slack. Don't try to explain it to them. They probably don't care, or if they do care, they're going to act like they understand and then walk away scratching their heads. This little breakup of yours is between you and her—no one else.
The other thing you'll need to do before you get rid of your girlfriend is to understand that being honest—with your soon-to-be ex and with yourself—is the most important way to approach any situation in a relationship. This is particularly true if you hope to ever interact with this woman again. Everyone appreciates honesty, and while it may be painful to tell her the truth, she'll appreciate your honesty once she's mourned the loss of your love and learned to accept that loss. Hiding things from people only leaves the possibility of rekindling their anger when they find out about it later.
The Quintessential Steps
An important first step in getting rid of a girlfriend is to find the right soundtrack to do it to. Now, you could take the easy path and listen to some "angsty" pop-punk, but let's face it, they don't know what a real girlfriend is. All they see during their world tours are hoards of screaming teenagers taking off their shirts and throwing their size 0 panties onto the stage. Unless you're one of these angst-filled pop-punk band members (or your girlfriend really is a size 0), you'll want to start sifting through those old hardcore power metal band albums you stopped listening to in the 8th grade. There's a kind of incomprehensible, ambiguous rage in that music, which you can feed on to build up your own incomprehensible, ambiguous rage.
Come up with one succinct, honest reason to get rid of your girlfriend. Something like, "You're not a size zero anymore," would work well. Or, you could tell her you're having a hard time understanding her these days. Let's face it, relationships usually fail for one of two reasons: bad sex or poor communication. A prime example of both would be "that one time" when she was getting a little too rough with you in bed and then she screamed another person's name. Whatever the reason is for wanting to break up, make sure you can summarize it in one very truthful sentence.
If you want to get rid of a girlfriend and keep both of your dignities intact, find a private place to tell her its over. There's going to be a lot of crying, maybe even a few of your own tears. You don't want people to see you cry, and you don't want people to see her cry because when your girlfriend cries in public, it's automatically your fault. That, and she's probably got a lot of choice words for you, as well. Breaking up with your girlfriend in a public place is a no-no. But avoid breaking up with her in your bedroom. You know too well the power of her feminine wiles. Try doing it in the dining room. It's hard to have spontaneous makeup sex on a cold, shaky dining room table. Better yet, wait until winter and break up with her outside.
Maintain your distance emotionally if you really want to get rid of a girlfriend. Once you've uttered those four words, "We need to talk," she has already started devising a plan to retain your loyalty to her brand of "love." Don't argue with her. Don't debate with her. She's smarter than you, and you know this. Keep your distance because she's going to address those two imperatives we mentioned earlier: sex and communication. She's either going to try to listen to your needs, or have sex with you—or both. Be strong right now. You can "manually stimulate" yourself once she's gone.
Whatever you do, don't listen to breakup music. That's her job. Listening to breakup music is only going to stimulate that part of your brain that still suspects there's a chance for you two. At this point, power metal might not be good for you, either. Try some classical music, or some jazz, or even some blues. Everyone knows blues musicians are of a singular message: woman done you wrong and she done left you. If you can convince yourself that she actually abandoned you at some point during the relationship, you'll have a better chance of weathering through the mourning period of the breakup.
No Communication, No Sex
These are the two rules for getting rid of a girlfriend for good, and this is the hardest part. Chances are you'll still see each other. It will take some getting used to the fact that you aren't having sex on a regular basis, at least with another person. If you can maintain a non-communicative, non-sexual association with your ex-girlfriend, you'll be better off for it. Your ex-girlfriend is going to get depressed. She's going to lose weight. She might even lose enough weight to fit into those size zero pants again. Then, other guys will start to notice her (if they haven't already), and she'll start to feel good about herself again. She'll start to feel attractive again. She might even get the crazy notion that things might have worked between you two if she had only tried to understand you better, if she had only kept going to the gym.
Whatever you do, don't talk to her. Communication is a gateway drug—to sex. Once you start communicating and having sex again, you're back to where you started, and in trying to revive the relationship you'll inevitably remember why you broke up with her the first time and the bell will ring for round two of the breakup bout. The question is, how many rounds can you go?