Because the low beam is working, the fuse & relay are good. The left handlebar switch has power in on pin 1 from the relay and out to the head light on pins 2 & 3. Low beam on pin 2, and High beam on pin 3.
The fact that the High Beam indicator on the dash doesn't come on, and the low beam works, tells me the switch or wiring is the problem. Electrical wiring problems are sometimes hard to locate. Take your time and think about each step and with some diligence you'll figure it out. Once you find it, should be a easy fix.