I'm sorry for not realizing how important this was to you
I want to take a moment to apologize for not fully understanding the significance of this matter to you. I now realize how important it was, and I deeply regret my lack of awareness. Please allow me to explain and express my sincere apologies.
I understand that my actions or words may have caused you distress or disappointment. It was never my intention to disregard your feelings or downplay the importance of this situation. I genuinely apologize for any pain or frustration I may have caused you.