I'm not going to help my boyfriend navigate while driving
Why wouldn't you help him navigate?
Because he is an adult and can be on his own for that.
If your boyfriend is driving then he can't navigate at the same time and you should be helping him. If you don't help, it only reinforces to him that you are selfish.
I'm not going to sit there arguing with him.
Why do you think he could drive and navigate at the same time? If you are riding with him the least you could do is tell him where to go.