fensiveness – n. a knee-jerk territorial reaction when a friend displays a casual interest in one of your obsessions.
I think that some of us have some fensiveness about the things that we deeply care about if we worry about the friend taking a bigger interest or having more success when we do.
I know I’ve felt fensiveness when I find a new game on mobile that I might enjoy and my wife sees it and is interested. Mostly because she’s a much better gamer and puts me to shame if we were really competing.
We aren’t, but there have been times I’ve worked for a period of time to get to Level 100, and then my wife starts playing and is all of sudden 100 levels past me in a short time.
From the Dictionary of Obscure Sorrows