What is it?
Like other mixed-orientation relationships, poly/mono or mono/poly relationships include people with differing identities or practices, in this case one monogamist who is sexually exclusive with one partner, and one polyamorist who has or is seeking multiple partners with the knowledge and consent of all concerned. From the polyamorist’s perspective, the relationship is poly/mono, and from the monogamist’s perspective it is mono/poly – either way it means negotiating relationship boundaries that seem unusual at least, and possibly bizarre, to people who are accustomed to conventional (serial monogamous) relationships.
In most (if not all) poly/mono relationships, the monogamous person has the option to have additional partners and chooses not to do so for a range of reasons. Often they just do not feel like it, some because they are monogamous by orientation and simply do not desire multiple partners, and others because of specific life circumstances. The unifying factor is that the monogamous person knows about and consents to the poly person’s outside relationships but chooses not to have outside relationships of their own.
This is not the same as a polyamorous couple in which both people are open to or have already had polyamorous relationships but currently appear to be monogamous because they are only dating or married to one person at the moment. Much like a lesbian is still a lesbian even if she is not currently dating anyone, these folks are still poly even if they are not currently seeing others. Rather than a mono/poly relationship, it would be poly/seeking (or rebounding, or whatever).
When it works
Trust is key for the smooth function of any poly relationship, and building true consent from a base of shared trust and negotiation is quite important for a successful poly/mono relationship. Generally this builds with discussion, negotiation, honesty, and trustworthy behavior over a period of time. In addition to the basis of mutual trust, a number of other conditions tend to foster mono/poly relationships
• Matched emotionally but mismatched sexually: Sometimes people who deeply love each other and click on emotional, intellectual, creative, spiritual, and/or political levels make wonderful partners in many ways but do not click sexually. When a high-desire partner is paired with a low-desire lover, it can be a tremendous relief for both of them when the high-desire person has access to other lovers. Similarly, when a kinky person and a “vanilla” person fall in love, a poly/mono relationship can allow the kinky person to have sex that involves pain or power exchange with others who also enjoy those practices. The arrangement also relieves the vanilla person from the burden of either having a kind of sex they do not like, or feeling like they are not meeting their partner’s needs.
• Long-distance relationships: People who travel a lot or live far away from their primary partners sometimes successfully negotiate a mono/poly relationship. This can mean an additional partner to keep the person who is left at home company while the other person is on the road, or an additional partner in a remote location for the person who spends time out of town.
• Disabilities and illness: Some couples who have one partner with an illness or disability that makes sex difficult or impossible will negotiate an agreement that allows the other partner to have sex with people outside the marriage or relationship.
When it doesn’t work
The worst way to begin any poly relationship is by having sex outside the relationship before negotiating non-monogamy, what I think of as the “Newt Gingrich Approach.” Saying “Honey, I’ve been cheating and now I think we should be openly non-monogamous” hardly every works out well, because Honey is already feeling betrayed by the cheating and lying. Starting out with a lie undermines the trust that is fundamental to functional polyamorous relationships.
Another thing that will destroy a polyamorous relationship is consent negotiated under duress. If the monogamous person has agreed to polyamory under duress, then disaster will most likely eventually ensue. Duress can take a range of forms – financial, emotional, physical, explicit, implied, or even unconscious. Agreements made under duress are not truly consensual because they come with some kind of threat to enforce the desired outcome; if “no” is not an acceptable answer then “yes” is not a real choice.
A common duress negotiation would go something like this: Chris prefers monogamy but agrees to Kacey's request for access to extra-marital sexuality because Kacey implicitly or explicitly threatens to leave if Chris demands monogamy. Negotiated under the duress of threatened abandonment, Chris’s agreement will most likely be brittle and prone to splintering when tested. Polyamorous relationships can be complex, and have an uncanny knack of stressing already inflamed points. If and when the inevitable complexities of emotions and time management begin to disturb the network of relationships, Chris will have a melt down and reveal that the relationship structure is not now and in fact never was actually acceptable at all. Such mono/poly relationships negotiated under duress are not generally resilient, durable, or happy.