My Fiance needs alone time and I'm spiraling

So my fiance and I don't live together rn. He's had a couple long days at work but we've been hanging out after. Today I had a really bad day with panic and nightmares and feeling unwanted. He helped in the morning but didn't text me most of the afternoon.

We were texting and I had the insecure "are you upset with me?" text. He isn't at all, but he said he's "feeling off today". I asked if he needed more time alone or if I could help in another way. He said more time alone. I said I wanted him, but I understood that his day and his family are exhausting and we're both introverts so I get it. I just made sure to ask him to call to say goodnight.

Now I'm spiraling. I feel like I did or said something wrong or when he was comforting me this morning he was secretly annoyed. I feel like everyone who talks to me secretly just wants the conversation to end and I feel so goddamn lonely. I worked on something on my guitar to try to distract myself, and I have a crochet project. We've been in a pattern of hanging out every evening/night and my head is swirling with all the reasons why he said he needs alone time and how it must be because I'm a burden. I always feel like an unlovable burden. I don't want to do anything, I don't want to try to make myself happy, I wanna just go to bed for about 15 hours.

BPD sucks. I got diagnosed a decade ago and it is a lot better, but I hate how his alone time can make me have all these horrible thoughts and feeling about myself. I'm oscillating between crying and chastising myself for crying. This blows.

EDIT: It's also four days away from my birthday and I hate birthdays so I'm extra self loathing recently.