Jealousy - Detrimental to a relationship??

C • 🦄 ✨Your average 19 year old princess✨🦄
I know a lot of people think jealousy is a bad thing and causes paranoia and trust issues, which I totally agree with - to an extent.
 
On the other hand I believe it shows you care for someone and don't want to lose them.
 
Thoughts? 
 
And just to be clear, I don't mean controlling or over-protective "jealousy".