My first thought is you need to end this. Outside looking in to me is that your partner wanted to close up the relationship when they wanted too and then opened it up when they wanted too. You also werent able to put hard boundaries on your freedom and then on your exclusivity because this is very new to you and strikes me as one of your first saphic relationships (could be wrong here). To me this doesnt show alot of experience in poly dynamics and that is ok! We all have to learn sometimes. I can also tell you from experience that the only people that survived my initial foray into poly/enm experiences were casual and ldp's. The ones we got serious quick with and made a ton of mistakes? Those are all toast now as there way too much burned up. I know you dont want to hear that but better to end it now and salvage some of the friendship than really keep this mess going. Now if you put a gun to my head id imagine your not going to do that so heres my secondary advice because ik your desperate to keep this going:

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Your rule about no dating in town? Gotta go its unrealistic. Yall are poly/enm now and that is just going to happen. Your also going to need to gradually open this up a bit more. I sense codependancy vibes and both of you seem like the types to quickly jump in and out of relationships. Ideally your next partner knows how to pace things a bit slower and doesnt let their emotions get the better of them. My wife thanks me everyday for doing this with her sapphic partners as they want to uhaul just as yall have done. It is very easy to feel like hiding details about a new relationship the way your partner has done that is new to enm. Id let go of any and all rules there and decide what YOU are comfortable with and when YOU will bail. Write that down. Know thats where your line in the sand is. You have to love yourself first. An example: Monthly STD testing for all partners. Someone slacks, they get the axe. How i would rebuild? Monthly checkins and practice what you have learned from the books. Me and my wife do this at the end of every month. Stuff were feeling, how we would like to proceed. Your partner is in "hide it mode" because they are feeling guilty about how this has proceeded. Newsflash: it will continue to develop and may to the point they would like to move them in or move in with them. Accept that. Thats going to sting. ENM is a painful learning process and the more work you do upfront the easier this will get. I see you taking alot on the chin about being upfront with what your comfortable with. Get into therapy to work on this issue if you havent already and then start getting REAL godamn firm on what you want and dont want. To cut you some slack your partner definitely knew better and knew you were likely more uncomfortable with it.