It sounds less like you're missing your ex, and more like that you're disappointed in the fact that the relationship failed. It sounds like you built up an expectation of your relationship with your ex, and when that ended up falling through, you feel let down. And it sounds like you can't decide whether to put the blame on her or yourself.

If I'm reading that correctly, I think the best thing to do is to acknowledge this fact, that the issue is not that you're missing the relationship, but that you're struggling with the emotional letdown when your relationship ended up being less ideal than you initially planned. Because if you keep thinking that the issue is that you're missing her subconsciously, you're going to get led to the wrong solutions. For instance, putting blame on you or her isn't going to solve the actual issue.

If we take this premise to be true, then I think addressing the real issue probably comes down to thinking about what your expectations were and thinking about how the relationship was never going to meet those expectations from the beginning (based on the examples that you gave). Ultimately, I don't know your situation, and I'm not a therapist. But that's my interpretation of what you wrote

There are times in life when we don't get closure and never will. Coming to peace with this can be challenging. Do what you can to enjoy time with the ones you love. Time makes it easier but there's no guarantee for closure, ever. Enjoy life the best you can. Keep going.

Lots to unpack here

But occasionally I find myself borderline stalking her

Don't do this you creep. Talk to her like a normal person or a friend (note - after you address the other points in this comment). I still talk with some of my exes, it's chill. You'll probably notice she's changed and you don't like her as much too.

There’s no changing the past, and if I could, I don’t think I would’ve reached the point where I am in life with my current opportunities if we had stayed together.

Good on you for staying strong with that. It's why you broke up originally and you fulfilled that. Good job.

I became a massive stoner

Don't do this. Despite so many people echoing the "pot isn't bad for you narrative", countless studies have directly showed it contributes to demotivation, and there's plenty of correlations to things like increased anxiety and other mental illnesses

In doing so she broke our promise of prioritizing our friendship over the relationship.

Half this post suggests you're a weirdo dude. First stop being weird. Then you can be friends.

I understand a lot of the reasons why I’m hurt and some are justified some are not.

You're gonna learn that just because you're hurt, doesn't mean it can easily be made right. What could she possibly do to unhurt you? Apologize and come back into your life? No, she's not gonna do that. Especially after everything you wrote before this. Focus on things you can improve and write off your losses (i.e being hurt) instead of letting them drag you down.

tell me I’m an idiot or an asshole to my current partner or something.

You will never have it all. People in stable relationships develop a crushes on other people, they miss your exes, and they see easy opportunities to jump ship onto someone else for a whole host of benefits (experiences, sex, money, whatever). Some people do, some people don't. But you will always leave something on the table.

If you're an asshole to your current partner, you're going to know that by the fact you're not treating your current partner well. But it really sounds like a case of you need to fix yourself before worrying about others.

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Apologies if my comment came off as a little brutal, but I want to be clear and not simply comfort you on it. Fix yourself.

By building context.

Other, new experiences with other, new people. Are they better? Worse? Comparable?

You won't know what it is like or what it even means to be "over" it until you have an idea of something else that will work for you.

I know it's kind of a given, but this is truly something that therapy can be great for.

I always write when I feel bad enough.

I wrote down about my bad feelings. I wrote a letter I pretended to send them - it helped a lot.
I created a tool I used to see where on my way on healing I was. I used a clicker to measure amounts of thought I had about them and made a chart out of it (It was awesome to see how the thoughts dwindle to nothing with time)!

You can also talk about it with friends, family and strangers.

I’ve been with my current partner for 15yrs and I’m still not over my ex. I just got used it.

If this was a highschool relationship my advice would be to just wait. I was devastated when I broke up with my highschool sweetheart but every year it became less important.

Breaking up is something you learn to do just like anything else. In my case I found out the person I grew into isn't someone the person I was seeing would have loved and the person I am now isn't someone who would love the person I used to date. Now all the emotions I had and all the things that I thought were important seem trivial

Hope this helps, and don't stalk it makes you weird and everything you're experiencing worse.

You keep thinking about them, because you have yet to find someone, who can satisfy the feelings you used to experience. Completely distancing yourself first is a correct step. You know what to do, you just need to do it. Meeting new people, let alone at a level of connection like this, is quite difficult, so try to fill your time with hobbies. The more involved, the better

Therapy. Seriously. It will help with everything.

Over time it doesn’t get any easier, the pain just gets further away.

I've been in your shoes. I nearly married my ex that cheated on me. You know what happened? Like you I tried to move on and ended up meeting my wife while my ex was trying to reconcile. She admitted that she screwed up and that we should start over. I ended up snubbing her in favor of giving my now-wife a shot. Almost 16 years later and it was the best decision I ever made relationship-wise. My mistake was thinking my ex was the only one for me.

It's okay to not have the answers. It's okay to take time to figure this out for you. But you need to understand that if your ex hurt you when you really needed them, that's not the person that is going to be by your side at all times - they failed that check already. Life is short and fleeting - don't waste your good years hoping something will manifest itself through all of the past drama. You're fantastic and someone is DEFINITELY out there that will appreciate you for exactly who you are.

There's lots of fish in the sea, and potentially there might be several people out there that might be the one - give this one a chance!

I don't think this is something that unusual (or at least I hope so lol). This is someone that played a significant role in your life, that from one day til the next is suddenly not there anymore. For me this felt a bit like a part of my everyday life just died. Although I'm not sure how much you can compare this to the grief from death I feel like there are some similarities.

As others have already said, it does get easier with time, where at some point you will probably notice that you haven't thought about her for some days and then from there on the times where you think about her get further and further apart.

I know that for me I also had some underlying issues that really exacerbated the situation in a bad way. Therapy helped here so much. Not trying to say that you necessarily need therapy, but if you think that you may also have some underlying issues I really think that this will help immensely.

Hope you can work through this and can get happier with your current situation and partner.

Some really good advice here and people really tried, wow, just really surprised that not all people on Lemmy are tech geeks... cuz, I have to say that I do have a hard time interpreting situations and emotions and knowing that I can write about my problems and have a bunch of people really get into the issue and give really good advice, that really really means a lot 😊.

Finding closure of some kind I think. Keeping in mind why you broke up, why it didn't work out, why there wasn't a future in the relationship, etc.

The relationship before my current partner of over ten years was really intense, I thought she was really the one, she was what I had imagined my ideal type was for practically my whole adolescence. But a spot of long distance and her parents disapproval had us in a bit of on again off again, where during one drunk call to me, she admitted to kissing other guys (at the very least), and that was enough for me to just go, "oh, I think our expectations are too different", and I was able to put a hard end to that. Yeah, I occasionally think of her, but more in the curious way you wonder about an old acquaintance.

I had a friend with a sort of similar situation to yours, he and his girlfriend mutually broke up when we were all graduating high school because her friends convinced her that long distance wouldn't work out. It really messed both of them up, especially since they kind of stayed in contact. A lot of weird stories there, but not really mine to tell. But he talked a few times about all the "what-ifs" and it feels like that's the hardest part in letting go of a relationship.

On the other hand, if you can convince yourself that the answer to "what if?" is basically "nothing good", I think that can help. Though, easier said than done, it's kinda like brainwashing yourself by focusing on all the negatives about them. Easy for me because of the cheating, but not so easy for my friend.