We have courses in Anger Management but none, as far as I know, in Jealousy Management. We don't expect people to work at their jealousy; indeed, we indulge them. In France, kill someone in anger and you will go to jail (in the old days, to the guillotine) for a long time; kill someone out of jealousy and you won't. In consequence, every Frenchman - or,at least, French film maker - dreams of committing a crime passionel.
Both anger and jealousy are things which consume us and with which we seethe. Both are disorienting and even disabling.
To those who suffer extreme bouts of anger, we say they must find other outlets than hitting us. (Well, almost always. I once worked for a very aggressive boss, who terrorised and terrified people. One day, his superior confided to me that it was no different in management meetings - and that they were just hoping that one day he would actually hit someone. Then they could sack him).
But with jealousy, we think we have to live with it. We regard it as incurable. I don't think this is the case. I think jealousy can and should be managed and, not least, because its consequences can be so destructive.
Someone sleeps with someone else, their partner finds out, and some mix of anger, hurt and jealousy - in which the last often predominates - precipitates them into the nearest lawyer's office and thence into the divorce courts. No one expects them to manage their feelings even though the consequences are financial impoverishment, neglect of any children, and - two years later - regret for what they have done. These kinds of passion are generally very short lived things, despite what dramatists and poets would have us think.
I think the first question to ask the excessively / obsessively jealous person is this, Why do you want to spoil things? You have a nice relationship with your partner, why can't you enjoy it? Why are you checking their text messages and emails? Why are you throwing a tantrum when they want to go out on their own with their friends?
In this way, you can begin to break down jealousy into different components - insecurity, anxiety, envy, sexual jealousy.
It's the last which most frequently turns people into killers. A good start would be to stop glamorising that. How tiresome, how boring, how unimaginative. Get a life, don't take a life. Your partner has slept with someone else? Get over it.