So you have a diagram showing two processes (in two swimlanes). There are two intermediate events happening in the diagram. The first happens when the bottom process receives some communication from the top process and the second when the bottom process sends communication back to the top process.
In the scenario you're describing where the process along the bottom reaches the first exclusive OR gateway then the second and then ends there will be no communication sent from the bottom process to the top. Using the exclusive gateway means that the flow of the process goes one way or the other. In this case the top process will remain waiting for a message that will never arrive.
I would suggest some error handling so that if the bottom process ends then it needs to make the top process aware and top process can then close out without leaving the process unfinished.