Philosophy has fairly treated jealousy as such, but rather literature and psychoanalysis has themed it as a subject of analysis.
The concept of jealousy may refer to a feeling or emotional state:
Despite feeling experienced when seeing others possess objects or benefits that do not have or that we would hold exclusively (definition close to envy in the sense that it does not have the desired thing)
emotional state of the person who wants to possess exclusively the beloved, layout accompanied by worry and suspicion. Unlike envy, jealous “owns” a person but feels that “possession” in danger.
The concept of jealousy in some philosophers
We can consider the whole work of Proust as dealing with jealousy, both object and starting point.
Proust, in Search of Lost Time, says about suspicions it poses to Albertine:
It is better not to know, to think as little as possible, do not provide to jealousy any concrete detail
Freud himself, presents jealousy as a normal emotional state. In essence, Freud thinks if it is not present in a subject, whereas it is suppressed and therefore the more active. These are cases of “abnormally enhanced jealousy” encountered in the analysis that Freud designates under the terms of jealousy “competitive” or normal, “projected” envy and jealousy “delusional.”
Here is an excerpt from On some neurotic mechanisms in jealousy, paranoia and homosexuality:
On normal jealousy he has little to say about the analytical point of view. It is easy to see that it consists essentially of mourning, the pain caused by the love object that is believed to have lost, and narcissistic humiliation, provided that the latter element is separate from the other leaves ; she still has feelings of hostility directed against the rival who was preferred, and a contribution of more or less critical self that wants to blame the loss of my own love.
Sartre in Being and Nothingness says we are jealous because others, by its unconditional freedom still eludes objectification (we would not be jealous of a table), but specifically being jealous is a try, unsuccessfully, to transcend the freedom of the loved one:
I make myself desire. Desire is a spell. This is because I can not grasp the Other that in its objective factuality, to ensnare his freedom in this facticity must be that it be “taken” as one says of a cream that it is taken, so that the To-Self of Others is flush to the surface of his body, it extends all through his body and by touching this body, I finally coming of subjectivity ‘other. This is the true sense of the word possession. Such is the impossible ideal of desire to possess the transcendence of the other as pure transcendence and yet as a body