This one is the site I've found a lot of helpful articles and info:
Tools and Coaching to go from Highly Sensitive to Happy Sensitive

Still I don't understand all this and it's confusing and people seem like either to accept it or say it doesn't exist but there is no bridge between.
I'm frustrated with all this.

In psychology/ neuroscience or watever there are currently two mainstream explanations, one is emotional contagion and the other is the theory or mirror neurons. But both are about the perceiver watching or consciously registering something which then causes the person to have the same emotions as the perceived emotions.
But this doesn't explain when you are not consciously observing and still feel the emotion.
Why aren't there studies or something, because so many people experience it but apparently if you are trying to talk about it the "scientists" and mainstream psychologists think you are crazy or whatever.
I'm so tired of how this world works.
(sorry, rant over)