Couples reunite every day regardless of the situation. Sometimes horrific circumstances are overcome and relationships are mended when it would seem impossible to do so. So the answer to the question seems to be an obvious 'yes', you can get your partner back.
Here are some things you should NOT be doing if you intend to mend your relationship and get your boyfriend back or get your girlfriend back:
Constantly try to explain that it really wasn't your fault.
Try to convince your ex that you will change for good this time.
Always apologize for everything.
Call or SMS over and over again, trying to get your partner back.
Spy on them or stalk them.
Try to find out what they're doing (checking Facebook, asking friends & relatives).
Beg them to come back (or not leave).
Try to convince them that if you could just "sit down and talk" you could iron everything out.
Try to realize that when your heart is broken, when you're battling to keep your relationship in one piece (or trying to put it back together again) you are probably not the most rational human being on the planet. It's an emotionally charged time. You are probably distraught quite a lot of the time. Your emotions are on an almost uncontrollable roller-coaster ride. Who could expect you to be rational?
It's not uncommon to be crying a lot at this time. You may feel the need to sleep more or eat more or act like a recluse. You may find solace in one-night-stands or booze or worse, drugs.
Be aware, if you can, where your behavior has changed for the worse. Turn to a good and trusted friend or family member to give you an honest appraisal in this regard. You must behave properly towards yourself and the others in your life if you want a decent shot at getting your partner back.
Listen.... You wouldn't go back to someone out of pity would you? You wouldn't take someone back because they were weak and whining and crying and completely dependent, would you? It's to be hoped not. And it's to be hoped that you know that you absolutely wreck your chances of a reconciliation with your girlfriend or boyfriend, if you are like that yourself.
Here are some tips on what you can do while preparing for the return of your partner:
Get, or stay, fit. Go to the gym. Power walk. Walk the dog. Ride a bicycle.
Catch up on all the good books you've missed in recent years.
Eat properly. Take cooking lessons.
Learn more about wines. Go on a course.
Try that extreme sport you've been thinking about.
Get closer to your friends and family.
Immerse yourself in your work or hobby, or both.
In short, don't wallow in misery. No one wants to be with a misery guts and least of all your estranged partner!
Get some sound, proven advice. There are many books available from people who have developed successful strategies and methods of reconciliation. You are not an expert in the area and what you are doing may well be hurting your chances of getting your partner back.
Unfortunately this is a circumstance where time is most probably not on your side. Your ex partners indifference towards you grows and grows with each passing moment, especially if you are doing the wrong things or doing nothing at all. Your lack of a plan and a method is making the job of getting them back much more difficult.
Most importantly, take the advice of an expert and act on it early. Play it safe. Do what has been proven to be successful.