In real life, an ending is often followed by a new beginning, so an ending in a dream can represent the ending of an old phase in your life and the beginning of a new one.
You may dream about an ending when you are unhappy about a change in your life. Your dream is telling you that you must accept that change, and the losses that are associated with it, is inevitable if you are to achieve your goals.
If you dream that you have reached the end of a situation, it can mean that you have wasted too much energy dealing with a difficult situation in real life, and it is time to let go of negative influences and move on.
A dream about the end of something can be a message that you need to decide which aspects of your life you are going to change and which aspects you are going to accept as they are.