I think my husband and I have a lot of boundaries/rules/agreements compared to some people, but they seem to be pretty stable for us after 9 months of negotiation, and we revisit our agreements regularly. I'm a bit reluctant to post this in list format, but oh well, it works for us, and I don't see that it's hampered any of our other relationships so I suppose it doesn't matter what anybody else thinks.
1. Home from weeknight dates by 11:30pm unless it's an overnight or otherwise discussed ahead of time (so people can get to sleep without being interrupted by somebody coming home)
2. Write down all dates in google calendar so we know what's happening when.
3. Tell each other BEFORE advancing any relationships to next step of intimacy. (we aren't jumping into bed quickly with people, so it's not a problem to say "I'm interested in making out with X" then "I'd like to have sex with X"
4. No taking recreational drugs with a partner without prior discussion. (somewhat unlikely to happen, but seemed something important enough to include)
5. Follow agreed upon safe sex rules. Let each other know if condoms come off or break. (so far one agreement was re-negotiated for a particular relationship recently, so I feel pretty comfortable that we are both doing well at being flexible when things change)
6. Talk to each other before telling someone else we love them. (more for my benefit, I don't like surprises, and since we live with each other and talk about our partners, it'd be very odd to not know the other persons feelings were growing before we were sure enough to admit <3 to somebody we were dating)
7. After an initial meeting with a new person (which is always coffee and not a "date" date, we do go home and talk to our spouse about how it went before planning a date. This one has been a bit of a challenge for my husband because he wasn't sure how to express this to the other person, but the gist of it is to say, "I have an agreement to talk to my partner before definite plans with new people, so I will email you later today" This became important because if a date is exciting but they tick a few boxes like - vary greatly in how they practice poly compared to us, isn't willing/able to meet in the middle or take turns commuting to dates (Seattle's a big place, gas is expensive), says something negative about another of their partners that seems a bit iffy, or turns out to be incompatible in some other way...it is good to have a slight break from new date NRE to reflect and have a second perspective, rather than a date being made and have to be cancelled after the fact. So far this did result in one single poly chick deciding she wasn't compatible with seeing my husband more at that time because she preferred dating people without restrictions like that. This is one that perhaps someday will go out the window, but as we've only been actively poly again for 9 months it is staying. You can tel I feel a bit defensive about this one or I wouldn't be explaining it so much
8. Tell each other about important changes in other partners sexual relationships and don't be intimate again if any risky behaviors have been introduced without discussing it with each other first. (new fluid bonded partners and STI issues basically)
There's things like make sure the sheets are changed and things are cleaned up promptly after dates in the multipurpose room dates happen in sometimes, there's a list of BDSM activities that my husband is comfortable with me participating in with others, and if I want to do them with somebody, I let him know the relationship is going there before it does. I've asked him not to date co-workers at this time because although he thinks it wouldn't be a problem, he's actively looking for a promotion.
I have agreements with my boyfriend also, which are to share if we go out on a date with somebody new, and to share if we are going to become sexual with somebody new.