long distance will work if trust,  clear goal and focus is the foundation of the relationship,  the moment neither of these 3 lapsed,  relationship will fail,  because if your in a long distance relationship,  if you don't have these 3,  for me you'll lack motivation and without motivation then your just aiming for nothing and if you don't aim for anything you'll end up with nothing and will give a glimpse of doubt to the other person,  and of course it should be worked by both of you.