Morwel, Faerinall, and Gwynarwhyf are all lovers - they all sleep in a big pile every night. They're not going to be jealous of one another. They're all pretty much married already, if eladrins understood what marriage was.
Eladrins generally don't understand human concepts of "cheating" - they're beings of chaos, and they don't really understand posessions, rules, or personal boundaries. They sleep with whoever they feel like sleeping with, and none of them ever get upset about it. Not only are they chaos incarnate, but they're also kindness and goodness incarnate; they understand and sympathize with one another, they would never do anything to hurt one another, and they like the idea of each of them spreading their love to as many people as possible.
Now, if we start talking about the archons instead - yeah, they could get jealous.