Creepy guy keeps staring at my girlfriend on her college bus daily. No one helps. What can we do?

So, my girlfriend takes a bus every morning to college, and there’s a guy who keeps staring at her continuously throughout the ride. This has been happening for quite some time now, and it’s causing her a lot of mental stress. It’s not like he follows her outside the bus, but as long as he’s inside, he just keeps staring at her in a creepy way.

One day, she finally confronted him and even shouted at him, but no one in the bus supported her—not even the conductor. Instead, some older men dismissed her concerns, saying, 'You’re overreacting; he’s just looking. What’s the harm in that?'

But do we really have to wait for something worse to happen before taking action? This is happening in broad daylight, yet no one is willing to step up and help. Worse, some people are even defending the guy, saying, 'It’s not a crime to look at someone.'

Can someone suggest what steps we can take to reduce her mental stress and handle such situations better? Also, if there are any legal actions that can be taken, that would be even more helpful.