So long as it's not much out of your way, IMO it would not make good business sense to drop such a job at the moment - not unless she persuades others to do as she has done. It may be an idea to inform her of how you work (in anything up to moderate rain presumably?).
IMO always ask yourself how much business sense a decision makes (as you have done) - though it can sometimes be tempting to follow the heart.
Effectively, she hs intructed you to check weather forecasts before leaving home I feel.
Unless a job is very lucrative, I do lose such jobs. However, I have a pretty full workload and keeping such work on would be bad economics. In fact, the last two times a custie has done this, it has been at the very end of the day and therefore cost me money because there wasn't time to go elsewhere.
I didn't like their curtains anyway
