My partner keeps apologising and I need it to stop

I love all of my partner very very dearly, and they tend to struggle with excessive apologising. They, at the moment, are struggling with their mental health and that does noticeably tie in with how frequently they apologise, even for tiny things that even I don’t notice, sometimes absolutely nothing at all. Back in April, before we were even together, I asked them politely to reign in it and it maybe got a little better for a time. Now, I don’t have an issue with the constant apologising because it’s “annoying”, repetition can be a trigger for me but thats the last thing on my mind; it really just diminishes the real meaning of “sorry” to me. I had explained this to them before that I would definitely prefer apologies to be left for the times I really need them, otherwise the weight of the word just gets completely lost. Well, we had a falling out not too long ago, and during it, there was a moment I definitely needed a real apology for something unrelated, and I was terrified because I couldn’t feel anything at all when it came. No relief, no calm, no nothing. They know the boundary I have set, yet they still choose to break it. I know it’s difficult for them, they overthink a lot, they need reassurance, of course I am more than okay with that. But the apologising is beginning to hurt, because theyre becoming so frequent that the ones I need don’t feel real. What can I do?