She replied to my message while I was going through an incredibly stressful week at work. I kept thinking I'd respond later, but later turned into almost ten days.
When I finally apologized, I expected her to ignore me. Instead, she said she'd almost unmatched because she assumed I wasn't interested.
We met a week later and talked about communication instead of pretending nothing had happened. That relationship taught me that a simple honest explanation is usually better than disappearing without a word.