It is ethical that when you do wrong to someone you apologize. However, saying sorry can be one difficult thing to do, in this case, just show your man that you are really sorry and you are making it up for him in this way:
Admit your mistake and apologize
It is a hard thing for many people to acknowledge that it was their fault even if they feel it. This is your boyfriend that you have hurt, cut down your pride tell him, "Sweetheart, I am sorry, I understand that it was my fault and that I overreacted". Since this is a hard thing to, he will know that you really mean it and you will be good again.
Use the power of touch
While saying sorry, hold his hands, look him in the eyes when doing it. Have you ever seen him blush? This will be the first time. When he says he has forgiven you, pull him closer and hug him like you really mean it. this way he will know that you are being sincere with your apology.
Surprise him
Am sure you know what he likes. For a very long time, he has been asking you to accompany him to watch a football match. Tell him that tonight you will be with him to watch that World Cup Quarterfinal match. Additionally, you can surprise him with a gift. This will show that you really mean what you are saying and you are sincere.
Promise not to hurt him again
Everyone is enthralled by the hope of a happy future and therefore after you have asked for forgiveness, promise him that it was only a misunderstanding and that it will never happen again as you have learned he was hurt and you don't want him to get hurt again.