Some couples cannot imagine the thought of marriage without ever being with another sexual partner, but others believe monogamy is a thing of the past. They see it as a trap and believe two people cannot possibly be committed to each other for a lifetime. They want to be with the same person for a long time, but that also agree that separate adventures are good for them. This is the basis of an open relationship. Each partner is committed to being with the other person, but each also has the option to seek out other partners at any time. They believe this enhances their relationship with each other.
There is no place for jealousy in an open relationship. Each person must equally accept that their partner will have the same options for separate sexual adventures. Both must accept the need to act responsibly with other people, including those that are their fuck buddies. Responsibility is important, and it must be a foundation if the open relationship is to survive.
The ability to have a fuck buddy while in a relationship may truly be an enhancement. Having a trusted person on the side that does not want a relationship leads to greater sexual freedom. It gives the person in the committed but open relationship a chance to learn more about their sexuality. They can then share this with their partner.
Most relationships do not function well when one or both partners engage in casual sex with other people. The lack of jealousy, combined with commitment, is not often found in two people. Those that can enjoy this type of relationship have found a partner that shares the same values they do. They have found a way to enjoy the freedom of being single with the security of having a trusted partner.