Certain points made by Marie de Champaign on the topic of (Courtly) Love:
(Source: Epistolae - The letter from Marie to Count G and Noblewoman A)
First, the obvious, "Love cannot exist between two people who are married" - the very basis of Courtly Love. Marie here gives the justification that true love can't be perceived in a wedded couple because they are already obligated to love each other and there's no challenge to the exercise of Love that gives its pursuit Value and Honor to both partners. True lovers are supposed to give Love freely of their own choice, without the pressures of society - family AND friends, who would all be thinking in Political and Feudal terms - glaring down on them. Which is why, other than the fact it is illicit (without the permission of family), Courtly Affairs have to be secret. Always.
Second is, IMO, a critical Rule of Courtly Love that modern fandoms would LOL @ but I think it should be given consideration: "No one can be in love with Two Men". In other words, "No Threesomes/Polycules, OTPs only". For the modern shipping fandom, it may come as a surprise and get a bit of a laugh BUT in the context with the first point above, it has very important purpose: It shows the couple is truly in DEEP Love with each other and not simply lightly engaging in eroticism with one another. Being in love with two persons means you are at best giving equal attention to both and not giving special treatment/preference to your "true love", which is supposed to be "proof" you are in deep love with that person. It's all about "The One(itis)" - the super specialest person in your heart that you would give up everything in the world in a heartbeat.
Moreover, it's another set of challenges for the noble pursuit of love, that there has to be a competitor, but ultimately, there has to be a winner - the chosen lover whom the Beloved has freely picked without pressure. Hence, there's another rule in Courty Love, which is "There is nothing that stops a Man from being loved by two women or a Woman being loved by two men" Note how I highlighted "being loved by" - there's nothing about loving towards two different persons at once. Which leads into the last point which is a very sensitive concept:
"He who is not Jealous cannot Love". Basically, if you really Love someone, you cannot bear to be away from him/her for too long and, more importantly, fear to lose or part with that Love. There has to be an element of Possessiveness. None of that Modern-style Selfless "I'll let my loved one go because I want him/her to be happy"; the prospective lover is one who, in the grip of True Love, has maintain the upkeep of the affair with his/her "Special Only". It's another way to prove you really love that person. If you are okay with another person taking away someone who is really dear to your heart, was that person really special to you in the first place?
