I am writing to apologize for my absence from the charity event our company held on Sunday to fundraise money for orphan children. In fact, my sister had already previously scheduled her marriage to the same night as the event as I could not miss this special occasion for our family.
I am writing you to explain the reason for my absence from the office yesterday afternoon,this is because I heard later in the day that you were looking for me. I had to be at the sales event organised by M&M yesterday, and I apologize for this as it seems that you were not aware that I was going out.