The term ‘living rent-free in someone’s head’ is often used to describe when one person becomes obsessed with another.
You do come across that in life and obsession is an appropriate word.
We can’t answer for others, of course, but we are responsible for our own actions.
If we find that someone is beginning to dominate our thoughts, we need to step back and analyse,
Ultimately, the happier we are with our own life, the less we worry about what others do with theirs.
There is definitely a link between the two.
There is more in the video, with other Thought For The Day messages via the home page.