Like what if the date sucked? e. g. I met this girl and we went on a first date with a lot of chemistry. On the second date, she was totally standoffish and wanted to leave like 30min into the date. At the end, I just thanked her and said I'm happy to be friends but can't offer more.
I've never ended a date on less than a happy note but I guess I could see w situation where I would. There's something called a second d ate slump so what you are describing isn't all that uncommon. For me I may have initially thought the first went well but then after time to rethink it realize we aren't compatible.