1. The purpose of an open relationship is to provide participants freedom, responsibility, and security. It is recognition that individuals can be intimate with different people at different times and still be committed to their life partner who can trust them.
Commentary: Building a life together is very different to a sexual relationship, and involves as much, if not more, trust and responsibility. A healthy mature open relationship usually involves trusting your partner about their other relationships, but your metamours are important in the life you build together and because they do affect you, you do have a right to opinions. It’s important to understand that not everything we tend to bundle together under the umbrella of a committed monogamous sexual relationship needs to go together, or operate under the same rules. Go slow, and talk to all your partners.
2. Communication and consent in all relationships are fundamental. When a partner seeks intimacy with another they must communicate this desire beforehand, to ensure that they can express any concerns, offer their approval, or even ask for participation. Both words "open" and "relationship" must always be satisfied. If they are not, it's simply the same sort of disrespectful 'cheating' that occurs in a closed relationship.
Commentary: It’s not essential that partners check before every new relationship or act of intimacy, but it’s essential that there are expectations and they are kept to. But I don’t think it has to be the same rules, so I think point 2 is more negotiated.
A check-in first is a good place to start, but people can have different rules, negotiated to mutual agreement. Some have rules like ‘must have met partner first’, some very much ‘do what you want in the moment, but let me know straight away and be prepared to drop it or re-negotiate’, some even have ‘I don’t need or want to know everything’ rules. Many seem to have different rules for different genders. There are ‘default closed’ polycules that requires consent from everyone involved. I have known multiple couples in fandom that had relationships with an explicit ‘permission granted in advance for anything at conventions’ agreement, and there are probably many with a similar rule for burner type events. And of course there is enough overlap between the ethical non-monogamy crowd and the swinger or queer sex party scenes that it’s explicitly covered in the rules for many open relationships.
Which is why I often use the broader ‘ethical non-monogamy’ term, though it covers a wider range than open relationship - because the important part is ethical, but there is more than one negotiable way to be ethical in a complex, messed up world.
The term "approval" is one which I had some hesitation over when composing this. I am influenced by one comment I saw that said, more or less, "seek approval, but there's no 'veto'; we're adults here".
Commenary: I find a ‘veto’ is something that many people find helps deal with anxiety early in establishing an open relationship. But it’s best considered the ‘training wheels’ of non-monogamy.
3. Be aware of the social biases against "open relationship", which often assume that it means it is a hyper-sexual "screwing around". It is important to dissuade others of this if one reveals this relationship status. Likewise, do not agree to an open relationship simply to satisfy a partner's desires.
Commentary: Of course, some people do like hyper-sexual screwing around, at least now and then, and if it’s mutually agreed and understood by all and responsible about the health (and mental health) of others, it seems ethical enough. But I agree that it is very important to make clear what is meant socially, and what your expectations are, and it can be a difficult issue at times. And open or polyamorous relationships can definitely include people that identify as asexual, and it can even be one of the reasons for being in an open relationship.
Some people use polyamory as a cover story for cheating. And some people find the emotional reality of what they intellectually believe to be hard to deal with, etc. People are flawed, and building trust is difficult.
It is a good idea to be wary of someone who professes an open relationship, but is very reluctant to allow open discussion with their partner about it. And conversely, a good sign if they encourage discussion with their partners.
But of course, life can be more complex than we would hope - neither is absolute, there may be issues such as mental (or physical) illness involved, people can have complex histories.
4. Always use protection. When one has intimate sexual relations with multiple people, a person generates a risk to both themselves and their partner.
Commentary: Always use protection is a good default rule, but it can always be negotiated. It’s possible to be responsibly ‘fluid bonded’ with more than one partner.
5. It is essential that partners regularly check with each other to ensure that they're on the same page, that needs are being met and concerns are addressed. An ongoing relationship is an ongoing conversation. This may result in changing of these boundaries which are firm at a point in time that must not be crossed, but flexible that if all approve that they can be changed.
Commentary: This is like the meta-rule. Open relationships need good communication, especially if anything changes, and everything can be negotiated and renegotiated. Renegotiating, or at least discussion that could lead to it, especially in a relatively new relationship, is a natural and healthy thing, as people's levels of trust and comfort grow.