Life is never what we expect. Even when we have a glimpse of the future, there are always changes. Is this karma?
It is certainly true that when karma comes, we never expect it. Even if we know it is coming, just before it happens we go blank and get distracted. You can never hold back karma. The arrow in the air from the past always lands in the present.
But karma is a teacher and not always responsible for changing our future. As we change, our future also changes. Only the universe knows the right way.
Whatever happens is for our better good. It is all in the hands of the universe. Trust that and be happy.