Sincere words
The girl forgave needed, above all, sincerity in the words. Not to say formulaic phrases, because she can just consider it all a farce. In the first place tedious to repent for your mistake and say you were wrong. Girls love it when they are right, it is flattering. If she responds positively, then the conversation can continue an explanation of the reasons which induced her lover to take such a step. Here you need to give serious arguments, otherwise it will not forgive, and even more lost faith in your boyfriend.
Explaining the situation, you should not shift their own blame on the girl, this will only get worse. Here, on the contrary need to take responsibility for yourself, then beloved, will understand that the young person can admit their mistakes and take responsibility for their words. To end the conversation recommended words about love, in this case, the girl will know that her real knight and forgive his wrongdoing.
Action
Sometimes words are never enough, and we need to do something more serious. It's a good idea not only to ask forgiveness, but to read a poem about love, and fit the poem. You can learn the excerpt from the immortal creations of Shakespeare, such a gesture will make an impression on her, and she will forgive her boyfriend. His speech can be reinforced by a bouquet of flowers, so beloved will see that the guy really cares, he cares and he will fight for it until recently. That's just the bouquet must be huge, all turned around in her trail. If there is a voice, then after an apology to sing a love song. Such a gesture will not remain unnoticed, especially if you do it not alone, and with witnesses.
Asking the girl's forgiveness, do not be afraid to show his emotions, because women live them. It is this recognition she will appreciate, because often men can be brutal and dry, and they need tenderness, the kid should demonstrate, and then he will deserve her forgiveness.