Scheduling conflicts make relationships very difficult. When you have two individuals who routinely travel for work, and are deep in the public eye, it would be very challenging to have a productive relationship. Since the two never had ample time to get to know one another without extensive scheduling and pressure, the relationship was probably doomed.
While I do believe their hectic schedules played a part in the break up of Tiger Woods and Lindsay Vonn, I don't think that is the sole reason it happened. Lindsey Vonn said in an interview on the TV show, "Late Night With Seth Meyers" that she didn't like golf. I think this is an indicator that the two had very different interests. I am also sure there is more to the story than we will ever know, because this is part of their private life. Not many people want to publicize everything that goes on out of the public eye.
Tiger Woods and Lindsay Vonn indeed have hectic professional schedules so I believe that was a factor in their recent announcement they were ending their dating relationship. However, other couples have stayed together with similar hectic schedules. They could have remained together and worked around the schedules had the level of commitment to the relationship been higher.
Tiger Woods and Lindsay Vonn seemed to do fine when either one or both of them were hurt. This is probably because they got to spend more time together recovering from their ailments. Now that they are both healthy, they are off doing what they do best and never see each other.