Those days that he missed

He stared at the calendar and realized what he missed. He missed her graduation day. He missed Christmas and New Year's eve but somehow managed to assumed that he was missing nothing. He did not miss her birthday but he is now wondering why he wasn't around on her birthday, and tried to remember whether he gave her birthday present or not. He missed almost all important events. On the other side, she tried to understand why he missed those days. Why she felt like she was not important at all. Why she felt like he took her for granted.