A sincere apology is just that, an apology. When you say I’m sorry to your boyfriend, do it with love, kindness and that you didn’t intend to hurt him. Forgiveness takes time, so after you say I’m sorry to your boyfriend, let the issue go; the next step is up to him.
There are numerous ways to say I’m sorry to your boyfriend, you could take him out to some place he would want to go, rent his favorite movie and supply the beer & snacks, get him tickets to a game he’s been talking about going to, write him a poem but the most special thing to do is to write as letter for him
Here is a sample apology letter to a boyfriend
Dear,
I am sorry for not attending your sister’s engagement. Believe me it was not intentional. As I started my car to reach your place with my sister a truck almost rammed into our car but with god’s grace nothing serious happened .I lost control and hit an old man. He was bruised and bleeding from the leg and the crowd didn’t allow us to move from there. We had to take the person to the hospital and there also the doctors were not ready to take him as it was an accident case. By then the police also reached there and made a huge scene about it. Finally we managed to convince the doctor and the police about what had happened.
The man was discharged with some stitches but due to all this we almost spent hours in the hospital after that we had to go along with the police to the station to explain what had happened and for some paperwork. By the time we were out it was very late in the night.
I understand how you would have felt and apologize about the same. I would personally come and meet you and your sister and explain everything. I assure you that I will be there a week before her marriage and we will have a good time together.
With lots of love,
Your name.