Cuckolding isn’t necessarily a vital part of FLR. But the pleasure, hapinness, and satisfaction for the dominant Female certinly is a vital part. The Female should make the decisions about sexual exclusivity in the relationship just like She makes the decisions for everything else. In other words She is completely free to find other sex partners if She wants to, and should be able to socialize independently by Herself or with anyone She chooses, not just with Her husband.
When a Wife is dating or with a lover, She may or may not be deny sex to Her husband. Chastity isn’t necessarily part of cuckolding, although it frequently is (as in our marriage)