When you visit someone and it's time to take food, that slight lack of comfort that you have to reach into the stew yourself to take whatever meat you wish is what shows that the house is not yours.
The same feeling comes when someone gives you the key to their car and gives you the go ahead to take it for a spin. You get in the car and when you are driving, all you can think of is the safety of the car and that nothing should happen to the car, it shows it is not yours.
The same feeling comes when you carry a baby that belongs to someone else, no matter how fatherly and motherly you are, when the biological mother stretches her hand for the baby, the baby will leave you without a second thought showing that they aren't yours.
The feeling of satisfaction and comfort only comes when you have exclusive right of ownership. This is a wake up call to put in more effort to get those things you see others have and you want.
Go get your own.
So many people feel so entitled to other people's stuff which is very wrong and it makes some people uncomfortable.