Complex sentence: They then realize as the events become closer that they cannot possibly go to all of the events that they had planned, this can be due to the events overlapping, or not having the time to fully commit to all of their previous plans.
Split into simpler sentences: They then realize as the events become closer that they cannot possibly go to all of the events that they had planned. This can be due to the events overlapping, or not having the time to fully commit to all of their previous plans.