I think this day is a great opportunity for you to teach Molly that some days just suck but that tomorrow is a chance to start over again. Sometimes life sucks. Sometimes we have bad days (maybe give her a not-too-horrible example of a bad day you've had). Tomorrow is a fresh start. When you put her to bed tonight you can remind her that today is over, say good-bye to it, and tomorrow will be another chance to have different experiences.

No parent wants their kid to have a bad day. I think it's ok to try to mitigate the crappy-ness of the day and help our kids back up and dust them off to try again tomorrow.