Well, I noticed as I progressed from an insecure to a secure attachment, that when I was insecurely attached to him I thought about him almost constantly and wanted a lot of contact between sessions so that he wouldn't forget about me. It was hard when he was on vacation because I was always anxious and I didn't feel comfortable unless I knew he was somewhere nearby, even though I knew I'd have no contact with him until he was back in the office. I felt threatened easily by thoughts that maybe he cared more for his other patients than for me, and I couldn't tolerate the thought that his feelings for me weren't as strong as my feelings for him.
But it's WAY different now that I feel securely attached. Of course I still think about him but I'm not preoccupied with those thoughts. I email him between sessions sometimes to let him know what's going on or to tell him about something I've finally understood or processed, but I don't need him to respond. Between sessions and when he's on vacation I can easily and comfortably pursue other interests and relationships without feeling the overwhelming sense of loss I used to feel. I can even enjoy the time when he's out of the office now because it feels ok to me now. I don't worry about whether or not he cares more about other patients, and I have finally become comfortable with the idea that he doesn't feel as strongly about me as I feel about him.
I feel very attached to him, but in a way that allows me to grow and explore, like a young child is able to do when she's securely attached. I don't need to cling to him like I did in the past.