I didn't think of the word "dedication". I think that's good word too. It definitely sounds a lot less cheap.
Also, my answer to your question is that I think this was a happy ending.
It's not happy like "happily ever after", but it's happy because the flower showed her love toward the fan, and I'm sure the fan would have been very happy to know that the flower will never forget about the fan.
When someone loses a close person, I think the person will mourn and be sad for some time, but eventually, I think he or she will remember the person who is gone and smile at the fun times they had. So the loss itself is devastating, but the memories are really happy.
So I think that if I had to decide between a sad and a happy ending, I would answer happy.
Does anyone else have other opinions?
