Possessiveness...What exactly is it?

Merriam-Webster dictionary defines the word "POSSESSIVE" as

Function: adjective
1 : of, relating to, or constituting a word, a word group, or a grammatical case that denotes ownership or a relation analogous to ownership
2 : manifesting possession or the desire to own or dominate.

To me, the word gives rise to lots of thoughts. What exactly is possessiveness, or when do we call a person as being possessive? More often the movies have portrayed a husband/wife getting angry over his/her spouse for silly things such as talking or dining out with someone of the opposite sex. But isn't that lack of confidence, understanding and maturity. Do we call it possessiveness, because the person is trying to dominate his/her spouse?

Is possessiveness confined to people alone or can it be extended to lifeless things also? Can a person be possessive over his/her car, Parker pen, SLR camera, fur coat etc. Is unwillingness to share these, a shade of possessiveness?

In an attempt to analyse both sides of the coin, I am considering a person who takes utmost care of his car. He cleans it daily, washes it once a week, and drives it within the limits without abusing it. When one of his friends asked his car for a two day trip, he refuses to give it fearing his friend may not be as careful as he is in handling the car.

What category does he fall into? A possessive person or a caring person? What is the line that separates the two kinds of people?

Can possessiveness be a higher degree of caring? Then the next question comes up. Is it good or bad? It’s bad because it hurts the loved ones and friends. So should a person be less caring to avoid being possessive?

Enlighten me.