Feeling pretty helpless while on a break in my relationship

I will warn people this is kinda long.

I’m currently feeling pretty stuck and helpless right now. I don't know if I should just start letting go before things are finally decided or hold onto some hope. I’m not sure what exact advice I’m looking for either, but I guess any thoughts or suggestions would be helpful if anyone has something to offer. I’m in a position where I’ve done all I can do and can only wait for the other person to speak to me about things.

About a month ago my SO of 3~ years called me and wanted to break up pretty much out of the blue because they stated the cliché “I love you, but I’m not in love with you anymore” yet they couldn’t give me any further explanation and then also stated they did not know if they were making the right decision. Rather than breaking up for good, we decided to go on a break and are currently still on that break, which is fine and I completely understand needing space to think for the both of us. It has given me time to evaluate things and I had written up an extremely personal, long, and detailed list/letter of some issues I recognized between us. I also provided suggestions to try to mend and rekindle things should they decide upon going that route. Some points are also reminders, personal feelings of mine, or observations that I felt we should possibly consider. There is a long-distance aspect of this relationship since we live four hours away and are in two separate countries, but we see each other at least once a month if not more. I think that in terms of what the future holds is also something that’s been an issue since we never properly talked about it. I know they are not keen on moving away from where they are, but as for myself, I would be happy to move to their area once I finish getting my degree and can find a job in my field. To give a TL;DR of the letter, I basically felt we had some communication issues and fell into a routine for a variety of reasons, and provided ways I was willing to work on things if they wanted to work on things as well.

I recently sent them what I had written and they responded that what I wrote really helped them out, but I didn’t know if that alluded to something good or not. They also said all the things I said were "good things" and that they hoped they could give me adequate responses. I told them they did not have to respond to the content of the letter until we actually sat down and talked about things, which we decided on speaking about it in what will be a couple weeks now. What makes this really hard is how our relationship currently is and how it’s always been. We met five or so years ago and became fast friends, and about three years ago we started dating. This has been one of the best relationships I’ve ever had and they have said the same thing. This is also the longest the both of us have ever been in a relationship, so we are both unfamiliar with how things work over extended time or what it feels like to just be going through a slump since all our other previous relationships have been a year or less.

Aside from being partners, we are also best friends. Even after we decided to take a break, we’ve been talking every day throughout the day about the things we normally talk about and stuff like that. It was just strange because even immediately after the day it happened, my SO never mentioned everything that had gone on. I ended up talking to them about some of the issues between us three weeks later before we were going to see one another for a weekend event we were attending in another city. I basically wanted to set some ground rules and figure out if we met people how do we introduce each other to other people and that kind of stuff. I also did bring up at the time that we desperately needed better communication between us and they agreed, and we’ve both started getting better wit that since then.

I have been trying to start to come to terms that they may want to end it and that I need to move on, but at the same time it’s very hard to do that while everything is so indefinite. I thought I was doing pretty well, even when I was with them over that weekend, but when we parted ways it was like everything I had been doing to start to come to terms with that fell apart. We had a great weekend together, which was fun, but it was also pretty strange as there was that elephant in the room type feeling at certain points. On top if it all, we are supposed to be seeing one another at some undefined time in the next few weeks to go to their family’s cottage for a weekend by ourselves.

I would understand ending things if there were reasons to that were harmful to ourselves or the other person. It's not like we're totally done with each other in the sense we don't want to talk/spend time together, have animosity between us, argue all the time, are unreasonable and unwilling to cooperate, belittle one another, try to control each other, disrespect one another, etc. – things like that that would be indicative of not trying to pursue things further since those issues would be lurking in the background waiting to resurface. We have a strong bond, similar interests, are supportive of each other, get along great, have a desire to spend time with each other, have fun with one another, talk to each other every day, and respect and trust one another. I think we just kind of became so comfortable with a routine that it became more of a companionship than a relationship. We are also both pretty passive people and are afraid to do and say a lot of things, which hasn’t helped our relationship grow. I already expressed to my SO in the letter this was an issue with myself and that I would start being more proactive when it came to things like this, which I’ve already started doing.

Only a few close friends and family members are aware of what’s going on with us at the moment since we’re both pretty private people. We have a mutual best friend that has talked to us both about this, and I think I’ve talked to them the most. It helps they know what both party is thinking and they are a good friend in the sense they won’t be like “oh so and so said” to the other person. However, I had sent the letter to this friend too before I sent it to my SO to make sure it was okay and my friend stated that a lot of things I covered were things my SO was worried about. My friend also did say that when they first talked to my SO about this, my SO seemed pretty set on just wanting to end things but at the same time they were so unsure of how they felt.

I don’t know if I should give up completely or allow myself to feel somewhat hopeful while still trying to prepare myself to move on, which will be very difficult to do given our relationship outside of being partners. I will respect whatever decision they do end up making, but I also hope we can have a chance to work on things. We’ve never had a huge issue before so I would find it somewhat odd if they just ended everything without even attempting to work on something that has been so meaningful to us for so long. Then again, that is their decision and there’s nothing I can do about that. I also find it kind of strange that they will only talk about this if I bring it up. Yet when I do, they are happy to talk about it and don’t seem to be avoiding it, if that makes any sense at all. They are under a lot of stress right now seeing as their family is moving (albeit to a new home in the same city), so that does not help on top of this, but I do not want to make excuses for them either. Some days I feel pretty good about the situation, and other days I feel like it’s doomed, which is pretty normal, but it sucks to go through. We are both young (23 years old each) and I know it's normal to have doubts and such, especially at such a young age.

I guess what I would like to know from anyone who took the time to read that wall of text is do you think this might just be some sort of rut we’ve gotten stuck in that has potential or should I really just try to start to really let it go so it won’t be as awful if my SO doesn’t want to work on possibly fixing things? As an outsider who does not know either party, what are your thoughts on our situation? Has anyone in a longer-term relationship experienced anything of this nature themselves before?

Thank you