Such as relationships, friendships, or love.
This sentence has no subject. It is incomplete. do it this way:
Jealousy is an emotion and typically refers to negative thoughts and feelings of insecurity, fear, and anxiety over an anticipated loss of something that the person values -- such as relationships, friendships, or love.
That way, it is all one sentence.
However, I don't think it is an accurate definition of jealousy! Jealousy can occur without a threat of loss.
Here is a run on sentence:
Jealousy is considered an advanced emotion, it is consisted of three basic emotions.
Do this instead:
Jealousy is considered an advanced emotion, because it is consisted of three basic emotions.
:-)