I'm concerned about my friend

Salaam everyone. I know the topic of friendships between men and women has been talked about a lot, but I have something on my mind that's been bothering me. I'm a sister, and my close friend, also a sister, has many male friends. Her intentions are pure-she doesn't talk to them with any wrong motives, and she truly believes nothing haram could happen. I've made sure she doesn't involve me with these brothers or share my details with them. But I'm really worried for her. If I tell her it's not allowed, I fear she'll think I'm judging her or asking her to leave friends she cares about. I make du'a for her, but I feel like it's not enough. What should I do?