I'm cross-posting this in r/polyamory and here because I'd like a wide array of perspectives. 32M here. Sorry for the length; I split it up into sections and added a TL;DR so you can just read this first paragraph and last if you want. Let me know if you need any other info. Here's my issue in a nutshell: my current girlfriend [28F] is forbidding me from being friends with my ex and this issue has got me so confused and seriously wondering if I'm polyamorous (or at least non-monogamous), which makes me feel conflicted about the future of this relationship. I need some clarity from people who are poly to see if you can relate at all or if you think I'm misunderstanding myself.

Background

I've only been in one serious relationship before. It lasted 7 years, through most of my 20s. That ended 1.5 years ago. I broke up with her. The main reason was my anxiety due to her depression and other mental health struggles. Living together, we were caught in a cycle of stressing each other out for years, but the good times (and probably my inexperience with relationships) kept us in the cycle. From the moment we broke up, I knew that, ideally, I would want her in my life somehow. I highly value her as a person, for so many reasons. It's just that us living together and being in that kind of relationship wasn't healthy for either of us. We wanted different things and we didn't live together well. However, I didn't rule out the possibility that one day, if it was healthy for both of us, we could be close and have some kind of valuable relationship.

The year following the break up, I focused on getting dating experience. Before my first relationship, I'd only dated very briefly. So from January - August, my main focus in life was getting good at dating. Long-story short, in August, I met the girl I'm currently in a relationship with. We've known each other now for 9 months.

The Current Conflict

1 month ago, my ex reached out to me via email. I was excited to hear from her. We hadn't been in contact for at least 7 months and I hoped maybe it was finally healthy for us to test out a friendship. My big mistake was not telling my girlfriend immediately when this started. I know that was wrong of me and not ethical; I completely understand that. My ex and I were only emailing once every other day on average, so it didn't seem like a lot. I half-expected her to stop responding to my emails (she'd done this in the past). And I knew with 100% certainty my intentions were not to compromise my current relationship or pursue anything sexual with my ex. However, when I finally decided to tell my girlfriend, she was rightly upset that I delayed telling her. But she was more upset by the fact I would want to be friends with my ex at all. This hadn't been something we'd talked about before because I assumed I wasn't ever going to hear from my ex again.

Anyways, this has turned into a huge conflict where my girlfriend has made it very clear that even responding to my ex's last email she interprets as a betrayal, and as me not making her a priority in my life. I completely understand that it was wrong of me not to tell her immediately when my ex reached out. But I've apologized profusely for that and tried to show her that she is very important to me and that my potential friendship with my ex has nothing to do (in my mind) with my very important relationship with her.

But internally it really, really bothers me that my girlfriend is deciding who I can talk to and who I can't, even when I'm being very clear about my intentions. I've told her very clearly: at the most, I imagine my ex being someone I might go out to get coffee with and to have a mostly conversation-based relationship with. That's what I valued most about our previous relationship. But my girlfriend doesn't accept this. Even telling her this makes her upset.

In an attempt to compromise, I even offered to send my ex one final email to explain the situation and why I can't communicate with her anymore, but my girlfriend didn't accept that, either. After I didn't respond, my ex reached out to me asking if I was okay. I'm not the type of person not to respond to an email. So now I don't know what to do.

I still do care about my ex. But I also care about my girlfriend. I don't want to hurt either of them. But my girlfriend doesn't understand this at all. For her, it's all or nothing: if she is part of my life, my ex can't be part of my life. When I search the Internet and Reddit for advice, a lot of it comes from a very traditional relationship-escalator, hierarchical perspective where you cut your exes out of your life completely when you commit to a new relationship. But I'm just not like that. I don't buy into that kind of thinking. I don't believe one relationship should be way more important than the others in your life just because you're having sex with them. The truth is: although I'm slightly aromantic and don't show my feelings in the stereotypical way, I can easily imagine myself feeling love for more than one person at a time without that devaluing either relationship.

Additional Info About Why I Think I Might Be Poly

When I dated, I put that I was open to monogamy or non-monogamy on my profile, and I did a lot of learning about different relationship styles, especially in the ethical non-monogamy world. The concepts of solo poly and aromanticism resonated with me the most. I've never had a problem with jealousy; I enjoy hearing about my girlfriend's previous relationships even though she doesn't share much about them. I could imagine my partner having some other intimate relationship(s) and me being fine with that.

I resonate with the idea of solo poly because I highly value my autonomy. I have no desire (and actually a lot of aversion) towards the ideas of marriage, living together, enmeshing finances, pressuring each other to spend time with the same friend groups or our families, monopolizing each other's time in general, the feeling of "ownership" and veto power that comes with "relationship escalator" relationships, etc. But I'm a pretty flexible person and I suspect I could be happy in the right kind of monogamous (or monogamish) relationship, one which allows me to feel like an autonomous individual rather than someones "other half."

My Girlfriend's Relationship Goals

My girlfriend, on the other hand, is very traditional. Think: Disney girl, rom-coms, and Taylor Swift. She is very romantic. She was the first one to ask me if we were in a "serious" relationship. She was the first one to say "I love you." She often asks "Where is this relationship going?" implying a desire to ride some kind of relationship escalator with a clear end goal in mind (marriage & cohabitation). She has made it very clear she would never want anything other than monogamy. She has made it clear she wants to get married "someday" although it doesn't have to be soon. At least we're on the same page about not wanting kids. But on almost every other relationship metric, we are different. She is constantly wondering (out loud) if I love her as much as she loves me, and if I'm as serious about her as she is about me, etc. This misbalance has been a source of friction for a while. I say "I love you" but oftentimes it feels forced. I've never been a very emotionally expressive or romantic person. It feels corny and unnatural to me most of the time (but not all time time). I feel strong affection and attachment for people who've been in my life for a long time, but I've never felt that overwhelming romantic love people talk about. I've felt horny, I've felt admiration, respect, and emotional attachment to my ex and my current girlfriend. But it doesn't seem like I feel that "I'd do anything for you / I'm crazy about you / you're my better half" energy that she seems to feel for me. This mismatch & our different relationship goals concern me a lot.

TL;DR: There are many reasons I believe I might be poly and/or non-monogamous, and this current situation where my girlfriend is very hurt by my interest in a friendship with my ex feels like a symptom of this. Where do I go from here? Do I give up on a possible friendship with someone important to me and pursue this traditional relationship with someone that I do really like, or do I cut this off before any resentment grows and pursue relationships that allow me to express myself and love in an ethical way that doesn't feel forced or restricted?

What do you think? I've shared almost all of the above thoughts with my girlfriend, but she doesn't seem to understand my perspective at all.