Obsession: A related term to intense preoccupation, obsession refers to unwanted and intrusive thoughts, images, or impulses that cause distress and anxiety.
Compulsion: Compulsion is the action or behavior that someone engages in repeatedly as a response to their obsession. It is often performed in an attempt to reduce anxiety or prevent something bad from happening.
Fixation:Fixation is an excessive attachment or preoccupation with a particular object, person, or idea. It involves being unable to move on from this fixation and constantly thinking about it.