I see what you mean about the place of fullness. I also see how much fuller his life was than mine. Although his relationships are mostly 'catch up at the pub' type friendships, he had loads more friends than I, so probably keeps himself busy out every night. He was always rushing out the door to do something, or going from work to something before coming home...a lot of the time I felt like an afterthought. He wanted to spend time with others, but less so with me it seemed. Like 'we' or I was never the priority. I don't know if he sees that now...he did say his attitude to 'together' had to change.
Whereas I have a few good friends and don't see them as much, but when we do it is meaningful. I have made efforts to catch up with people more, but it's usually once a week I am out if that. So my nights and weekends are quiet. Although I start uni again next semester, so that will keep my nights busy, but solitary. I am quite shy. Find it hard to keep conversations going, to approach people etc.
I know I need to get to the point where I am ready for a relationship with someone new. I know I don't need to rush it. I also know there is no point wondering why he got into a new relationship so quickly...perhaps she was the catalyst for the change. I don't know.