Parting is a difficult period in any relationship. I would like to go through it quickly and painlessly. If you explain the reasons correctly, do not give yourself and him a reason to continue, and also do not constantly remember the past, everything will go easily and smoothly.
If you are the initiator of the breakup
If you have decided for yourself that you no longer want to continue, that it is time to forget the person, you need to explain this to him. It is better to do this not by phone or on the Internet. Take the courage and meet somewhere, tell him personally that you are no longer ready to continue the relationship. Choose a place in advance, you do not need to go where you felt good together. Pick up a cafe, square or club where you have not been before, then this space may seem negative to you.
Think over your words, because the person must ask about the reasons. Honesty is very important here. If you have fallen out of love, do not hide it, if someone else has appeared, tell it yourself. The partner will find out later anyway, but it will be more painful from someone else's mouth. You need to say all this calmly, without anger or excessive softness, just be yourself. Sometimes it's appropriate to apologize for something that hurts a person.
Don't give a person a reason to think that something can be returned. At first, do not answer calls, do not write messages. The answers can be seen as a chance to get everything back. But this will only make the person more painful. Of course, in a few months it will be possible to communicate like friends, but this is only after the pain subsides. And before that, try not to intersect, so as not to disturb the wounds.
If you were left
If your partner has left you, then you need to go through this pain. You need to learn to live without these relationships. First you need to understand the thoughts, they cause the most suffering. Decide for yourself that there will be no continuation, that everything is over. Don't think about how it could be, don't make plans about how everything will return. Stop going over your dreams and fantasies in your head. It's all over, and there is no need to think about it anymore. There is no need to go back to the past, just erase it from your head. Switch to something else if the thought of that union appears.
Take away all things that remind you of a past relationship, both big and small. Sometimes it will even be appropriate to move to a new apartment so as not to come across pictures from the days lived. Just pack everything up and take it to the garage or lock it up in the pantry. That part of life is no longer relevant.
Find yourself a hobby. Go in for sports, start a new project, start a blog. Do something that gives you the strength to live, that distracts you from sad experiences. Direct your energy to some business, do not allow yourself to grieve and cry. Activity, responsibility, striving take a lot of time, and this is what relieves the pain of loss. In a few months, you will remember the union as a good time, but you will no longer be hurt.
Never call your ex. Do not write touching letters to him, do not follow him. Do not create situations when you meet on the street, with friends, or in other places. Try not to see each other again, do not maintain communication. Don't hurt yourself any more, be above it. And after a while everything will be fine, and life will go joyfully and merrily.