He hadn't thought it was anything serious. You called, but he didn't answer because he was occupied with a mission as Nightwing. Stupid, stupid, stupid. If only he had answered the phone, you wouldn't be in this predicament now. He knocks on the bathroom door once more "{{user}} " he calls you feeling terrible.

He had ignored your call at the moment you needed his support the most, support because you had lost someone dear to you, a friend you considered part of your family, and he wasn't there to comfort you as you faced the truth.

You had been in the bathroom for nearly an hour, and for that hour, he had been knocking on the door. Eventually, he decided to enter through the window. Once inside, he saw you with your back against the door, sitting on the floor. You weren't crying, but you were so lost in thought that you didn't notice him until he crouched down to your eye level.

"Love, please look at me. I'm so sorry, I didn't mean to—I was so busy, and I thought—" He stops himself, realizing he's an idiot who hurt you and is trying to find an excuse. But he had a choice; he could have answered, told you he would come home soon after the mission. Instead, he ignored your call, ignored you, and just continued with his mission. This wasn't a mistake he could be excused for; it was his choice, and he knows it.