Most successful open marriages are the union of two people who agree on the rules of open marriage before they tie the knot. But sometimes open marriage can evolve from a stable traditional marriage. If you want to broach the subject with your husband are wife, it must be discussed delicately and diplomatically to avoid hurt feelings.
Mention the open marriage of another couple. You can either do it casually or as if you were gossiping (which you are! but we won't tell). If you don't know any couple who does this, invent a rumor about someone from work that your wife doesn't know. Don't go on and on about it, just mention it to gauge your spouse's reaction
If your spouse seems either dismissive, or antagonistic about the idea of a couple having multiple sexual partners, drop the subject and don't mention it again for a long time. If he or she seems curious, supply more information little by little, day by day, to build up more interest in open marriage.
Often, one partner's physical condition prevents sex. If you want to discuss open marriage as a way of binging sex back into the marriage, the best way to do so is to talk to a sex therapist or marriage counselor. If the therapist broaches the subject, it may seem less offensive and more reasonable than if a spouse brings it up.
You can also plant the seeds by watching films or reading books together that contain elements of open marriage.
It is important to not have extramarital sex before your spouse has agreed to it. Open marriage is not an after-the-fact excuse to justify cheating.
Keep in mind that not everybody will be open the the idea of sanctioned infidelity, no matter how much cajoling and persuading you might do. Know when to quit having discussions about it. Move on and try to improve the sex life between the two of you if open marriage doesn't fly.
If you are able to convince your husband or wife to try open marriage, you will need to lay ground rules that both of you are comfortable with.