A breakup is a difficult experience for both of the parties involved. You may be sobbing so uncontrollably and begging for another chance that you hardly hear your ex boyfriend say that he would like to remain friends. Of course at that time you don't want him as a friend, you want him as your boyfriend. Seeing your dreams of a future with the man you love fading away can make you lose control and say things you don't mean.
In fact, you might have lashed out at him when he suggested being friends and said some things you now regret, but you might still be able to have him as your friend. Don't call him because you will probably start crying and begging again. Just send him a text and say that you are sorry for your actions and hope the offer of remaining friends is still open. He will probably accept at once because being friends means that you won't be desperately trying to get him back.
The advantage of being friends with your ex boyfriend is that you can keep in touch with him without being rejected. Just make sure that you never mention dating or love. Make the time of each conversation short and cheerful and try to make him laugh at least once every time you talk. Keep him talking about himself and if he has a problem with his job, school or family sympathize with him, but don't try to give him a solution. If you give him the wrong advice, you could lose him as a friend.
You biggest challenge will come when he calls you and starts telling you about his new girlfriend. This could cause you to start crying again, but if you can stay calm and listen to what he has to say and then tell him you are happy for him, you can completely gain his trust. For a few calls he will be extolling the good points of his new girlfriend, but you have to be patient. This is no doubt just a rebound romance and soon he will become disillusioned with her.
When your ex boyfriend begins to complain about his new love, you have to stay neutral. Don't take sides against her or your ex will start defending her and stop calling you. Being a good friend is being a good listener and the more you listen the more your ex boyfriend will talk. However you need to be the one to end the conversation each time. This puts you in control and makes your ex boyfriend want to call you again soon because he is not talked out.
When he decides to dump his new girlfriend, you will be the first to know and you will be there to console him. It won't be long before your ex boyfriend will want you to be more than just a friend and he will want to date you again. Take it slow and act like his friend for a while. Make him be the first to say I love you and don't be too fast to respond. The way to keep your man is to always be his best friend as well as his lover.