Hi guys!
I'll keep our relationship history short: My partner (24F) cheated on me (23F) two years ago. For months after finding out, I kept asking her to be honest, but I eventually went through her phone and discovered she was still flirting with person who she cheated with and talking about a future together. They had fallen in love and wanted to be together but also include me and his partner. Later, my girlfriend told me that nonmonogamy felt like the right option for her (for various reasons I won’t list here).

After attending couples therapy for the cheating, we started working toward an open relationship this June. Before anyone asks—yes, I also want an open relationship.

Now to my current situation: Lately, my girlfriend has gotten close to a guy from her work. The person she cheated with was also a mutual friend and colleague. Recently, at a work party, some of her colleagues made mean comments about her and this new guy, saying things like, “Does his girlfriend know how he behaves?” or “That’s not okay to your girlfriend (to the guy),” after they went off together to grab some wine.

My girlfriend admitted she’s worried she might develop feelings for this new friend. I told her it’s okay to communicate openly, and we’ll decide what to do if feelings arise. At first, I brushed it off and defended her, saying those comments were unfair and slut-shaming (which I still believe).

But yesterday, I felt a wave of jealousy because the situation reminded me of the past cheating. I’m almost 100% sure she’s not cheating now, but I worry she might omit things or unintentionally cross boundaries in the future. I decided to talk to her about my feelings and asked for reassurance that she’s clear on my boundaries and our current agreements.

Unfortunately, she felt attacked. This stems from our history—early on, I struggled to express my feelings without sounding accusatory, though I’ve improved a lot. She told me she doesn’t want to be “babysat” and wants to take care of herself in this situation.

That response really hurt me. I felt like I couldn’t rely on her to hold space for my feelings of jealousy, and I felt rejected for the first time in a long time. I communicated that, and she apologized, saying she’ll work on making future conversations better. She clarified that she knows and respects our agreements and truly wants us to work.

However, after this, I had trouble feeling close or connected to her, which is now an additional issue.

My question is: How can we handle these situations better in the future as we navigate an open relationship? I want her to work on her defensiveness, and I need to work on not withdrawing after feeling rejected. Jealousy conversations are difficult for us, and I feel lost because I want them to be healthy and constructive. I know jealousy will resurface—likely more often as we continue this journey—so we need a better way to address it.

TL;DR: My partner (24F) and I (23F) want to transition to an open relationship after cheating and couples therapy. She’s recently gotten close to a male colleague, triggering jealousy for me because of a similar past situation. I communicated my feelings and concerns, but she got defensive, which made me feel hurt and disconnected. How can we have healthier conversations about jealousy and boundaries in our open relationship going forward?