Partner changed after developing chronic pain and left me. Should I fight for our relationship or let him go?

Hi everyone, I need advice. I haven’t been coping well with a recent breakup.

I (24F) met this guy (24M) four months ago and we had an intense connection right away. It felt like fate and like I had met my soulmate. He talked about a future, kids, moving countries, introduced me to his family, and made it feel very serious very quickly. We did long distance and I would fly 8 hours to visit him often, staying with him and his family.

After the first month, we started having communication issues and arguments, especially over text (he doesn’t like calling). During fights, he would sometimes break up with me, then take it back and say he didn’t mean it. After a few weeks of this though, things improved. Up to our last week together, he continued to reaffirm that things were better and that I had improved how I handled conflict, and for a while it really did feel like we were moving in the right direction. But everything went downhill after he got sick.

He fell ill with chronic migraines/headaches and daily pain (neck/jaw/shoulders), and started to turn into a completely different person. He became constantly irritable, would snap at me over small things, and I felt like I couldn’t connect with him anymore. He couldn’t think clearly, couldn’t sleep properly, and we were both exhausted from dealing with it when I would visit. I tried to be understanding and not escalate things because I knew he was struggling enough to begin with.

On my last visit, we were supposed to go on holiday together. A few days before flying out, he had a night of complete insomnia after taking some pain medication. On our trip two days later, we had a small argument that escalated. It started because I asked him to walk beside me instead of ahead of me since my feet hurt from the flight. He took it as criticism and got upset, and it turned into a bigger fight.

While fighting, he said he didn’t see anything long-term between us anymore and he didn’t think our personalities were aligned. He cancelled our trip, booked another hotel, and left the next day. I flew home because it felt too painful to continue without him.

What confuses me is that just days before, he was still saying I was his soulmate, that he wanted a future with me, asked me not to give up on him because of his behavior from the pain, and talked about long-term plans seriously.

Why would someone say such serious things about a future together, calling me their soulmate and talking about kids, and then suddenly break up and say they don’t see anything long-term? I’m really struggling to understand how both can be true.

He’s also been under a lot of stress outside the relationship (moving back in with his parents, adjusting to strict office work, and being in constant pain for 2 months). I can’t help but think this contributed to us not working out.

I don’t know if he really meant the breakup or if he’s overwhelmed by all the external stressors and ended the relationship because it was the only thing he felt he could control. I still care about him and don’t feel like we’re fundamentally incompatible.

Should I fight for the relationship or let it go?