I have known Ting for a long time. She was a friend of mine in high school. Ting used to see me as her best friend in my class because, as she said , it was easy to be friends with me . Therefore ,when we had time in school,she often came to me and we would talk about many things. Though I didn't have special feelings about this friend, _ because I didn't see the reason why I should say "no" to a friend I didn't hate. But there was a while when she came to me, and usually said nothing meaningful. I started to feel tired and then tried not to meet her. After that she never came to me. Though guilty, I started to feel free about my life and never thought of anything about her feeling. After a month or two, I heard from other friends that Ting's father had passed away six months before. I was so shocked! Then I suddenly realized why Ting had often come to me but said nothing special. She needed my company  . I felt so bad about myself that I went to find her the next day. But I only found that she had moved away to another place. At that time, I found myself so selfish that I only thought of myself but didn't even try to ask a friend what happened in her life.   _  because .... What does "this" mean here?
Ting's coming to the writer. The things Ting said. The writer's own feeling. Ting is easy to be with.