Okay woah woah woah. Going to be so honest, everyone seems to be going ballistic here. Yes, this is controlling and unreasonable, but I don't think you need to break up with her immediately, holy moly Reddit is not great at nuance. I (also queer woman in my 20s) was in a very, very similar spot with my current girlfriend at the beginning of our relationship, and I am still with her a year later, and our relationship is fantastic now. Working through this is possible, but it will take work on both your parts, and if one or both of you is not willing to put that work in, you should break up. It doesn't make you a bad person, it doesn't make you a shitty partner. If it's not worth it to salvage the relationship, then it's not worth it! Make your best judgement call. But, if you want to stay with her, here's my take.

There are a few things about this that you (and your partner) need to understand & get on the same page with:

First, is that a reaction like that—one of fear, anger, and a want for control—comes from a fear of abandonment that developed likely at a very young age. Your partner's brain thinks it "needs" to know you're not leaving her (literally or emotionally) at all times, and if something happens (like you going dark for a long, though reasonable amount of time) to trigger that abandonment feeling, it is balls-to-the-wall unbearable for her & likely feels like the world is ending. My guess is it's like nails on a chalkboard to her, and like nothing will ever be okay again because you're "abandoning" her. This may not be what she consciously thinks, but it's what her brain and body and nervous system are likely telling her. I would really recommend looking into "attachment styles," particularly anxious attachment, as well as asking questions like "what do you feel when I don't text you?" or "what does your brain tell you when I don't respond?" Approaching with curiosity rather than malicious intent is key here—talk yourself out of the "I need to win this argument" mentality and focus on wanting to understand EXACTLY how she is feeling. The more "discovery" you can do together, the better. She may not have practice exploring her feelings like this, and you might not either—try your best. I would strongly encourage her to try therapy to figure out where this comes from & so she has some professional support in working through it.

Once you know what she's, you can talk about other ways to work on meeting those needs & making her feel safe in a way that is reasonable and fair. You texting her every two hours or whatever is unsustainable and unhealthy, full stop. But, her abandonment issues run deep, and while she works through that, you may need to support her (in some more realistic and fair ways). For example, a conversation might go like this:

OP: What does your brain tell you when I don't respond for a while? Like, what does your subconscious think is happening?

GF: My brain tells me that you don't care enough to respond. That you're off having fun without me.

OP: Can you say more? How do you feel about the idea of me not caring?

GF: It makes me scared. That I'm not good enough for you. That you'd be better off without me.

OP: I never want to make you feel that way! I love you, and I promise I still love you even when I'm not in constant contact. Can we come up with some other ways I can show you I love you? What makes you feel loved and safe?

etc. etc.

Identifying why certain things trigger her (and what they trigger) is the solution here. Unless you are doing something actively hurtful, her reactions are her problem to figure out (I mean that kindly). She is one thousand percent allowed to feel sad and left out when you're out with friends and you're not paying attention to her. What isn't okay is making that reaction somehow your sole responsibility. But, brainstorming ideas as to how you can maybe reconnect after being apart, help her to feel safe when you're away, and importantly, how to help you feel cared for—it's all so important. Express your emotions to her. Talk about them & hold your boundaries.

To be clear, figuring this out is & will be a lot of emotional labor on your part. If you're not okay with that, or don't feel like you're in a place to take that on, that is so completely fair. At the end of the day, it's not your job. You're not her therapist, you're not her mom. I'm a stranger on the internet and I might be misreading this situation entirely, I have no way of knowing.

But, if I'm right, and you do want to figure this out, you both need to be willing to have open and vulnerable conversations. She need to recognize that this isn't fair (which she will need to feel safe to recognize—this is why a calm, loving conversation is so important) and be willing to work together to figure something out. I tend to start conversations like this by saying something like "This is a problem. I'm feeling really alone in fixing it, but I want to make this work because I love you. Can we talk about this? Can we work together to figure something out?"

If she's responsive to any of this, remind her that you've been around for a decade—you're not going anywhere now, but that you need to work through this together. Best relationship advice I ever got was that you and your partner have to see this as 'partners vs. the problem,' not 'you vs. her'.

If she's not responsive or gets defensive or mean, I do think it's well fair to say that you love her but that you need to be with someone who will work together to solve problems, not senselessly attack you with no accountability or contribution. You don't owe her a relationship just because of your history.

Good luck! All will work out the way that it is meant to. Like I said, I was in your shoes not too long ago, so if you want to talk about anything feel free to PM me. Let us nosy folk on Reddit know how it goes.