The voltage in this circuit is mainly determined by I*R. The diode is OFF until it has enough voltage across it (V_F). Then, once it is ON, it locks in at V_F, limiting the resistor current to V_F/R. Any additional current goes through the diode.
Play with the applied current and watch how the voltage locks in once I*R = ~0.7 V. Then, any more applied current goes through the diode, which is now ON. Meanwhile, the resistor current stays failry constant.
