Certified GKH Gardening Expert
Kale is treated as an annual, and will be harvested as it grows. Once it starts to flower, it will be discarded. Likely, your kale is nearing the end of its life.
As for the larger plant that died- It sounds like the kale may have been placed into a container that was significantly larger than the one it came in. This will usually lead to overwatering, and infection. This will lead to the death of the plant.
What I can do from here is offer an article that will help you with the proper care of Kale in container. This should help prevent future issue.