Cuckolding (scenario 1: The cuck is the submissive)
Platonic expression: Committed marriage (basis), possibly a polygamous marriage. The practical/survival part of the relationship, and the emotional love connection.
Sexual expression: Cuckold relationship, where the cuck acts like “a protector” and the partner acts like a spoiled teenager with all the sexual freedom and finances they need… The cuck is sometimes included in the sexual relationship, sometimes not.
“Unhealed” expression: Marrying with a secret intent or assumption that cheating is a given factor in a marriage, and that love between married partners is automatically unconditional but no forthright conversation is required before finding a sex partner outside marriage.
The need to be in a cuckold relationship can be either a phase in spiritual development or the end goal, depending on the people involved.
The idea of a cuckold relationship is to allow one partner to be sexually involved with anyone they want (or perhaps with a gender limitation), while being financially taken care of by an official husband or wife. The cuckolding partner can be seen as the King or the Queen, and their partner a submissive servant of his or her needs.
(See scenario 2: The cuck as the dominant.)