Managing Jealousy in an Open Relationship

My boyfriend and and I have been together for 2 yrs. We both agree that it's okay for him to sleep with other women and for me to sleep with other women when we aren't sleeping with one to share. However this has not happened yet for either of us but we are actively looking and talking to other people. How do I control the jealousy that has surprised me. I find myself incredibly jealous and sometimes even heartbroken thinking about my boyfriend sleeping with another woman without me there even though the idea wildly turns me on. Am I not ready for the poly lifestyle? Any advice is appreciated!! 

All due respect, this isn't a polyamorous lifestyle. This is swinging or an open relationship, which isn't a bad thing. But polyamory is specifically about having multiple romantic relationships, which is not what you or your boyfriend are seeking and my genuine hope is that you are both very, very honest about that with whomever you encounter.

Understanding the link between monogamous socialisation and jealousy

It's not surprising that you're very jealous of the thought as well as heartbroken. You've grown up (most likely) within a mono-centric society that has taught you that love and romance look a specific way and that's also very likely why you also find the thought arousing. Even though your language here is kind of treating these women as objects in a way (e.g. "one to share"), you recognise that you are essentially in a privileged position as the girlfriend. And there is only one girlfriend and if there is only one space for one girlfriend, that means you can be replaced. Of course, this is always true and will always be true, even if your boyfriend was not allowed to sleep with anybody else.

Exploring ethical avenues for sexual adventures

In general, I believe it's likely that this feeling will pass and just be something you will have to deal with. I also think that if you and your boyfriend are looking for just a fun sexual time, you may want to actually, provided it's legal where you are, seek out the services of a sex worker or potentially go to swinger clubs or other groups where people are intentionally looking for people to have sexual adventures, not relationships, with. If you are attempting to find specifically women to date, I think it is likely that, especially if you use the language you're using now, you're unlikely to find anyone who is going to be interested. I would in the future also re-examine these rules when it comes to what seems like a one penis policy here. You might be okay with having it, but there are also a lot of people within the polyamory community who would find it unethical and therefore may not want to be involved for that reason.

Why the one to share approach can deter potential partners

It's likely that your approach will even scare off people in the polyamory community who may actually fit what you're looking for. Even myself, who is wholly now uninterested in cohabiting or in any form of primary relationship and may not necessarily mind dating two people who just so happened to be in a couple, if I fancied both of them, would avoid any one who talked about having "one to share" between them. Even if I'm not interested in being in a primary relationship and wouldn't mind being in a more casual formation with two people, I still don't want to be treated like a piece of meat that's going to be tossed the second that emotions start becoming an issue. My relationships still have meaning and are still deep, even if they are "casual".

Finding a path toward more success and less conflict

I think if you were to seek out other people who are looking for sexual adventures or hire a sex worker, it is likely you'd still experience some jealousy, but there would be less there for you to be technically challenged by and you'd likely have a lot more success.

I hope this helps and good luck!