There's an interesting discussion in Poly & Kinky over on FetLife entitled Deal breakers? asking other polys what they would consider unacceptable in prospective and current partners, which has prompted me to share my thoughts on some of the deal breakers listed in the thread (in no particular order):
"I am looking for someone who completes me." I want to date a whole person, not a half of one - nor do I want to date someone looking for zir soul mate or THE one. I have come to find that I am incompatible for those who consider themselves incomplete without a partner.
Cheaters. Sometimes the cheater likes to dress it up with how zir current partner doesn't understand zir 'poly nature' - but cheating is cheating is cheating. Rather than trying to see if they can work towards opening the relationship together, zie decides that their partner's feelings are irrelevant. Yeah good luck with that, bitch, but I'm not the one.
"I have a high sex drive too, so I can understand why you want multiple partners" or "Open relationship? Oh sure, I'm cool with keeping things casual" or "Were poly, there's no such thing as cheating." Poly and commitment are not mutually exclusive. Anyone with this view of poly has a fundamentally different outlook on it than I do and shows that we would be incompatible in a relationship.
"We only date as a couple." I am thinking of making this an entry unto itself because I could rant a novel on the subject, but I'll keep it simple here. Since I believe a relationship is between TWO people no matter how many are romantically involved, I will not date a couple. I will date two people that happen to already be a couple, but I do not date those that structure their poly as 2+1. Not only is it a disservice to the third by not allowing the third to form zir own individual relationships, those that structure their poly this way tend to have unreasonable requirements for said third (in the poly community, they're known as Unicorn Hunters). For example, the couple often demand that this polyamorous third not date any one else or they expect the third to have ONE equal emotional response to the TWO of them. If one partner in the couple feels this agreement has been breached, the offended partner can end zir relationship with the third AND zir partner's relationship with the third (also known as 'veto power'). I don't see any benefit as the third in this type of relationship.
"You can date other women, but not other men." I would never agree to an OPP (One Penis/Pussy Policy) and am also thinking about making this a post on it's own. I have heard about this working in the poly relationships of others, but I have yet to hear a reason for implementing this rule that wasn't: a) selfish b) based on sexist ideology c) that wasn't about avoiding an insecurity rather than confronting it.
Anything that involves keeping secrets from anyone's partners. As expressed in my entry School of the Hard Knocks, this was an ugly one for me to learn and I still have all of the knocks to prove it. I didn't think I would have to ask a partner not to put me in a position that would compromise my relationship with the other partner. Now, I set this boundary upfront to avoid similar unpleasant surprises.
Needs to have relationship maintenance talks nearly every day. I'm all about communication in a relationship but unless we're dealing with a crisis or some other major event, maintenance every. single. day. is overkill. Husband associated conflict with progress and would often create conflict to facilitate (what he perceived to be) progress. I let him know early on that I couldn't spend two hours rehashing fairly inconsequential shit EVERY DAY because I found it to be tedious and draining.
A history of unstable, volatile relationships or seeking other relationships when your relationship is unhealthy. You can get an idea of what kind of partner someone will be and how you will be treated by looking at how zie handle zir past/current relationships and partners.
Trying to talk me out of current relationships. A person that tries to breakup an existing relationship in the attempt to have the attached partner all to themselves is termed a cowboy/cowgirl. Anyone that tries to 'take me' from a partner has a different idea of poly than I do and shows that we are not compatible.
Someone being attached to a belief about how I feel despite being told otherwise. Husband also had a habit of doing this - though never towards me, only towards Wife. (I never understood why he took me at my word but not her, considering she was always more upfront about her feelings than me.) He acted based on what he believed she felt rather than what she expressed about how she felt. It was very strange and frustrating (and is partly how he justified many of his lies and manipulations of her).
Poly personal ads that read like job postings. I've never understood in the poly (or kink) community why people who are looking for someone to love include that this person must also be willing to help clean up around the house, pitch in with the kids they have from a previous relationship, and is expected to be available for kinky sex involving additional partners. When I was monogamous, I never saw an ad open with these things so I don't understand why people believe "I want a house cleaner, a nanny, and a sex slave" is an attractive offer to a poly partner.