I'm new here, and have mostly been reading threads about the dreaded A. I decided to take some time and peruse the other sections to get my mind off of things (It worked!!). I'm not an 'expert' per-se, but I do have quite a bit of life experience with this topic.
About me:
I am a fully out-of-the-closet 2nd degree Wiccan Priest (That means I am perfectly imperfect )
I have been married (hand-fasted) for 15 years to the greatest love of my life whom I have been with for 22 years total.
Before my bride, I was married twice before. Both were tragic, world-ending events - both cheated and the 2nd broke every rule we agreed upon. I also spent alot of time in open relationships, non-exclusive 'arrangements', and an open marriage.
First, I want to say - from experience - that if you are fresh out of a failed M, the thought of this lifestyle may seem like a good idea. I would caution against it. It's not for everyone. Being able to Love (in that way) more than one person at the same time, without guilt or secrets is not easy. You have to be just as open and honest with each of them, and most people seem to have a hard time with one (I learned that the hard way). It can be exceptionally rewarding, especially if you are like me and want emotional satisfaction all of the time, be it talk, sex, or whatever.
In my experience, to be successful in these relationships requires alot of maturity. You must be willing to treat each person as if they are the only one but also be honest about it with them and yourself that, in fact, they aren't and neither are you. That's not an easy task, and many of my past lovers walked away because they realized how hard it was. I like to call those people 'dabblers'. They think they want it, they agree to it, and then realize "wait, you do this with them too?". Yeah, it's like that... a lot!
Many people will say "I'm poly" and they really mean "I just want multiple partners without commitment". Being poly means commitments. You enter each relationship with the understanding that you are just as committed to one as you are to any others. It also means you are just as committed to the fruits of those relationships.
Poly's usually have a primary. This is the one that they have chosen mutually to be the bride/groom. They are the one that shares a home, makes babies, pays bills... etc. The rest are more like fiancees or steady dates. You love ALL of them, would do anything for them, and will be there 100% when you are there. So you have to ask yourself if you can really be "that guy/girl" for more than one person.
At the same time, you have to also remember the old adage: What's good for the goose is good for the gander. You have to fully understand that, even your primary, each of your lovers will have other lovers. Accepting that notion is not easy for most. You also have to realize that break-ups are just as hard for polys. You will have it happen, sometimes because the person didn't really want it or maybe tried it out and changed their mind. Perhaps they decided that they wanted to be YOUR primary and since you are 'taken' in that regard, decided it would be better to separate for both your sake. It's no different than monogamy in that regard, it just happens more frequently. You also need to realize that this can happen to each of your lovers. And you need to be there for them to console them honestly, just like anyone else you love.
You also have the added concern of protection. You MUST be fully willing to tell the absolute truth about your sex life with everyone you sleep with. Who are your regulars, who is your primary, have you took a 'shot in the dark'? You have to be willing to tell all and hear all.
That's not everything on being Poly. But it's a good start.
Now Open relationships, including OM, are different in some ways and sometimes develop into a Poly situation. You don't have a primary and secondaries in OR/OM technically. You have your main squeeze, and some friends with benefits or one-night-stands or both. Many who think they are Poly or want to be actually end up here. The boundaries are the same idea. The Main Squeeze is your anchor. They are the one you prefer usually and generally, when given a choice, will choose. You still treat the others well, but you aren't 'committed' to them like you would in the above. The problems faced are sometimes the same, but there are a few differences. FWBs are friends first and you need to treat them that way. That means if they are in similar circumstances as you, both of you need to be honest with not only each other, but with the other lovers. Jealousy is a mean bastard. The safe sex and protection rules always apply. Weather it's a relationship or M you don't necessarily want kids with a FWB!!
Non-Exclusivity is like OR/OM lite. You don't want to have sex with just them, but you aren't intending it either. It's like a get out of jail free clause. I personally think many BS and WS are thinking of this when they dabble with OR/OM and poly. Lets face it, your life has been turned upside down, you're hurting, maybe having self esteem issues, and certainly afraid to commit. But you still have needs and desires.
When my first marriage imploded, I was the BS. Maybe some day I will tell that story, but today is not that day. I met another woman pretty fast, and she was there for me through the divorce. We had never agreed on exclusivity or anything. We were just having a good time. After a while, we got serious. We decided to have an OR that morphed into an OM. We had a beautiful little girl and life was good. The thing was, she didn't actually want a real OM. She wanted to never be held accountable for what she did with who. She wanted FWB that happens to be married. I never hid who I was seeing and never took risks. There were boundaries about who we could and could not sleep with. She crossed every one including unprotected sex with ONS and the like. We didn't last long after that, and I still to this day consider her to be a cheater.
My Bride, who I met about a year after, wasn't interested in dating at all. She just wanted a good time, and that's what I gave her and didn't see her again until 6 months later when I asked her to be my girlfriend. I cheated on her. It led to me breaking it off. I spent months trying to move on from it and finally, even though I didn't have to - since we were no longer together, I went to her and confessed. I apologized profusely and begged her forgiveness. I didn't ask her back, I told her I never expected it. She wanted me back. It shocked me - alot.
We agreed that, for the time, we would have an OR. She only slept with one other man during that time. It was really that she wanted to see if I would run with it, and at first I did. But after 5 or 6 years, I found my self taking a knee and proposing to her. I told her she had 2 options: Be my primary, or be my only. She chose to be my only and I never looked back.
Now I'm telling you this story so you can see the Pros of poly/OM/NXR. If done right, it can be - and is - a wonderful and beautiful thing. The Cons are very hard pressing though and can lead to many hurt feelings. I said I had experience in poly, and I did. In between marriage #2 and this one, I was poly for a while. I had at one time 4 serious girlfriends, a primary, and even though I am not bisexual, a male companion that that I loved just as much as my ladies. I am no longer friends with the women. They unfortunately were not truly poly, but the man, yes. I have never been his lover, and never acted like his boyfriend, but we are very good friends because he is truly poly.
So how do you figure it all out?
Well, I'd suggest this. Get out some paper and a pen, make 3 columns and label them Want, Will, Wont.
In the Want column, put down things that you want. Do you want multiple sex partners? Do you want more than one serious partner? Do you need to love more than one person? Do you want a house? a better job? All of it. Then look at the will column. What are you willing to do? Sex positions/acts, have multiple partners, Multiple Lovers? A mortgage? Cosign on a non-spousal loan? All of that. Then the Wonts. What are you NOT (can change BTW) willing to do? and do the same. Sometimes it's easier to start with the wont list because we usually KNOW what we DON'T want, but seldom what we DO want. Once you have that list, you can start looking at your life and choose how you want to share it with others. Maybe you just want good friends and pure unadulterated non-attached sex. Maybe you're really a closet poly! You have to find out. And FYI, there's nothing wrong with dabbling. Just make sure that you use phrases with people like "so you know, I'm poly curious". That way there's no deceit, because honesty is the best policy.
Now I didn't learn about the want/will/wont list from her, I have understood the concept for a long time. But a really good place to learn alot about poly and other relationship styles is a youtube channel called sexplanations. She's a legit sex therapist and talks about these things alot. If you haven't seen her videos, got watch some. She's brilliant.
And of course, I expect others will have more insights into this topic. I just wanted to leave my $.02 on it. I look forward to reading your comments, discussions, and additions.