A lot, if not most, sufferers isolate when overwhelmed. Either deliberately, as a tool (before things get too bad), or just naturally in response (once the limit has been reached or crossed and it's meltdown time).
Try considering it like having a migraine, for needing a few hours of elsewhere, or the stomach flu for a few days. Having both PTSD & having gotten sick? I compare the two an awful lot. Just like getting sick? Sometimes you can feel it coming on, and sometimes you're just fine at 2pm and laid out by 3pm. Ditto, sometimes you can suck it up and press on even though you feel bloody miserable, at least to work, or maaaaybe if you sleep all day, you might be able to keep an obligation that evening, or might could spend some time growls and mumbling at your mom/spouse/best friend but could never hold it together for your boss, or a store clerk (and sometimes the reverse)... and other times? There is simply no way. Same token, if caught early? A day of rest can mean you pull out just fine when first fighting it off or first getting better, but a day of overdoing can mean weeks of ugh, or relapsing and getting sick all over.
And just like getting sick? It is no reflection whatsoever on how you feel about your partner, job, or anyone else in your life. You're just sick. And need to take a few days to recover. What that looks like? Depends on how hard you were hit, and how well you take care of yourself vs overdoing it.