magnetic and electric field lines DO NOT EXIST in space. Its like on a wheather map. We draw lines of equal air pressure onto a map so that we can IMAGINE how fast the air pressure will change from one point of the map to another. If the lines are near together the pressure changes fast if they are wide apart the pressure changes slow. However there are no LINES in the air. If we draw all lines for each tiny pressure change onto a weather map it will go completely black and gets useless. To apply a certain spacing between the lines we need to leave some finer lines out. This does not mean that there is no airpressure between the lines. I am writing this because I have the feeling that you interpret the lines as surfaces or boundaries of electric or magnetic field. They are just a human invention to make visualization easier.