Depends on the person, in some cases it could be both.

I RARELY attach to people. I've lived my life keeping people distant and not caring much at all if they are around or not. However with my dogs....I have/had deep attachment, due to loving them so much that I was afraid to lose them.

Then things happened with T, and its similar, I think the love feelings are very strong and so the fear of losing him has combined with it as well. Makes it a nightmare for sure.