"If someone would feel jealous in a polyamorous situation, then I would actually advise them to stick with monogamy. Polyamory isn't good for everyone. You need a certain amount of poly hardwiring in order to be happy living a poly life."
If agree if they can not conquer sexual/romantic jealousy, they should stay mono. However, I think one of the problems of conquering sexual/romantic jealousy is how it is institutionalized as a virtue. You notice when two siblings are jealous over one another for the love of their parents, people automatically make the assumption that this type of jealousy is a psychological problem or at least a psychological handicap. Yet when people become jealous in polyamory it is perceived as a sign that poly is IMMORAL especially when they strong relate it to sex.