Partner has questionable anger coping skills. Stuck feeling lonely.

Seeing thru a possibility of getting better? Does it actually get better?

I’m struggling with what to do from here. My (24M) partner (27NB) (together 3 yrs) just can’t seem to regulate their emotions when things go wrong/not their way. We are in a LDR at the moment, but used to live together. My partner has a history of getting really angry/frustrated over certain situations, and taking a moment by themselves to cool down. I’ve been okay with this in the past, and have given them space. But, it becomes difficult to empathize when the things that set them off become trivial. Earlier, I had accidentally gotten rid of a portion of a holiday dish we were preparing. We had plenty finished and refrigerated for later, but the remains of the sauce was intended to be saved for later meals. It was a dumb mistake on my part, but they got super upset. Expressed my name angrily, then retreated into another room and shut the door. I felt sort of awkward, as being in an LDR makes me feel like much more of a guest in their house. I also find myself explaining away this sort of stuff when others are around, I.e. while their roommate was joking about my mistake and letting me know it’s no big deal, I also had to tell him my partner is not okay right now due to a food related mishap(?). I live 7 hours away, so Im also very stuck in their space. I’m never sure how long it will take them to cool down. They couldn’t really find any non-frustrated words for me, but also let me know that we were fine and they just needed time to mourn the hard work and money (I paid) they put into the dish. Most of the time I can’t distinguish if they’re actually upset at me, or the situation. I’m okay giving space, but the trivial stuff, especially triggered by my relatively minor mistakes, really hurts me. Obviously it makes me feel as if their episodes are my doing. I also felt disappointed, as we only have a limited amount of time together and we hadn’t seen each other in months. Maybe it’s my anxious attachment style, but I don’t think anyone likes their partner abandoning them to fume, then go to bed without a word over a Tupperware of sauce. They claimed they’d work on it after I spoke to them, but it seems to be something they’ve always done on occasion. Usually they come around in a few hours and apologize, but sometimes I can’t take their total emotional abandonment at unpredictable moments. I just feel shitty and incapable of focusing on anything else. They say it’s nearly impossible to find kinder words when they feel this way. I’m not sure what to do.

TL/DR: My partner copes with anger/frustration in a way that makes me feel bad sometimes. Advice?