I think I am pretty weird when it comes to jealousy, especially in the context of relationships. I know many people who subscribe to the thoughts of St. Augustine: "He that is not jealous is not in love". I have a fundamental problem with that because of what it suggests. The quotation that somewhat expresses my sentiments is by François, Duc de La Rochefoucauld: "In jealousy there is more self-love than love".
Jealousy involves three parties: you, a person you see as a rival, and something, or somebody you desire. With jealousy, your focus is more on the object of desire than your rival. When you are jealous, you are afraid you could lose that thing or person to your rival because of an inadequacy you perceive yourself to have. In a sense, it says "if I can't have him, you shouldn't either", which connotes some element of malice. But more importantly, it says, "I think you are better qualified than I to have the object of my desire", which connotes a feeling of inadequacy and a lack of self worth. The other side of the coin, where a person expects to be jealously guarded also suggests feelings of insecurity since the person's feelings of self-worth are predicated upon someone else's actions.
Envy, on the other hand, as Aristotle describes it, is "pain at the good fortune of others" even though it does not take anything away from what you already have. It is one of the 'seven deadly sins'. Envy is when you wish you had, or want something that someone else has, or when you think: "why should they have this and not me?", but there is no impending loss. With envy, because the focus is more on the rival than the object of desire, if that good fortune went to someone else, the feeling of envy would die out. Envy occurs when your standard of self-worth is defined by how it compares to others. Taken further, it can be the dislike of another's well being or good fortune because they are not deserving of it, in our sole (and not so humble) opinion.
I don't consider myself jealous. Indeed my love has been called into question on occasion because of my lack of jealous inclinations. But I have realized that I cannot hold on to another's affections - like an egg, if you don't hold it tight enough, you will lose it; and if hold on too tightly you will break it. Jealousy also engenders suspicion, which, in turn erodes the foundation of trust that relationships are built on, and eventually, like a house of cards, the relationship comes crashing down. Suspicion makes one look for reasons to question another's loyalty, and, in most cases, you will eventually find what you've been looking for - akin to a self-fulfilling prophecy.
I have learnt that while I hope my relationship with the person I love will last forever, I cannot control the other person's feelings or actions. I am with them because they choose to be with me and that is my blessing and good fortune. I cannot say I will not be hurt, disappointed and even angry if they decided not to be with me, but I will understand that it is their prerogative and sole right to decide who they will be with; a right I have as well.
I think benign envy is par for the course because of our innate desires and the pursuit of life, liberty and happiness. We will always see someone with something that we wished we had. I know I do. Will I cut them for it? Absolutely not. I will be happy for them but it will spur me on to be in the position to be get what they have that I like.
I can understand envy, but I despise jealousy in any form because it is a sign of weakness and tells me so much about the person it is coming from. Jealousy, in my opinion is not attractive and screams "Extra Baggage - Beware!" and all its attendant abandonment issues, and I shy away from such energy. But I also realize that for many people, they need to see some element of jealousy to make them feel wanted and desired.
There is an Arab saying that goes: "Love sees sharply, hatred sees even more sharply, but jealousy sees the sharpest, for it is love and hate at the same time..."
Something to think about.