Dear Mark,
I’m writing to you to apologize for my absense without having told you. Thank you for the invitation, but I had some university problems that I had to solve. Let me explain everything.
Our professor gave us 3 days to make a group project. However, I and my groupmates had realized that we didn’t even start thinking about it. That’s why we decided to have a meeting and perform the task as soon as possible. But, at first I was planning to go to your party, ’cause I had made a special present for you. Unfortunately, the deadline was on your birthday, we were rushing and everything slipped out of my mind as I was busy.
I wanna apologize for this incident again and hope you’re not offended. How about going to the bar next weekend? We could have fun together indeed. I will be waiting for your response.
Cheers, Lina
