Dashed dreams

I'm trying to decide if false hope is maybe a little bit good. Two examples from this week: one, I was reading a murder mystery for book club and thought there were twenty pages left, then they solved the murder. I thought for a minute that there would some crazy twist, the murder wasn't really solved, but it really was. Two pages later the story ended and there were fifteen pages of 'bonus' interviews and excerpts from the next book by the author. Two, I was waiting for a train home in the cold wind and saw one coming. Expectation seemed to raise my body temperature and a smile crossed my face, but alas it was the reflection of one coming the other way in the curved, frosted glass of the platform. I think hope is always a good thing, even if it's fleeting (I am an optimist). Maybe the lesson is not to put too much emotional investment into the dream so that you're not totally crushed if it turns out to be dashed in the end. (I'm not sure I like that; it sounds a little pessimistic.)