Sometimes I get really upset when people stare at my wife

As-salamu alaykum, I'm a Muslim living in the West, and there's this one thing that's been eating at me for a long time now. My wife is Muslim too, but she doesn't wear hijab. She explains that she isn't ready, mostly because of her career. She's concerned about being treated unfairly or possibly even losing her job. She does have the intention to start wearing it, insha'Allah, when she feels the moment is right for her. The problem is what happens when we're out in public. Whether we're at a cafe or the mall, I often see men giving her looks. It fills me with such a burning anger that I just want to say something to them. What really gets to me is that, a lot of the time, the ones staring are actually other Muslim brothers, not people from outside the faith. My usual way of handling it is to just glare back at them until they look away. But there was this one incident that I can't forget: after we had already left a restaurant, my wife mentioned that a man had been staring at her the whole time. She said she tried to make eye contact to get him to stop, but she didn't tell me while we were there. When I found out later, I was furious that I didn't get a chance to do anything about it right then. Even now, months later, I still remember it. Honestly, I think I'd feel a lot more comfortable if my wife was in hijab, but I know this is her choice and her journey to make. I'm really wrestling with these feelings of anger and wanting to protect her. I don't want to overreact or do anything that isn't good character, but I also have this strong feeling of wanting to guard her beauty from those looks. Has anyone been through something like this? How do you handle it when you're in that situation? Any advice would mean a lot. Jazakum Allahu khayran.