Women are the ones who are most aware that listening isn't merely a passive activity. It requires effort and is an action. Sometimes a guy is stressed out about work, has something important going on in his life, or is pursuing a goal.
When you sit down, maintain eye contact with him and engage him in a genuine discussion about a topic that matters to him. It will convey your concern to him.
I've heard some terrible tales of men who are ferociously jealous of their girlfriends or who refuse to "let" them go out with friends, particularly with other men. Although I can understand the fear, a man should have enough confidence in his relationship—and enough trust in his girlfriend—to stop worrying whenever she is out on her own. Text him occasionally throughout the night to say hello if you have a boyfriend who is old enough to urge you to go out and have fun. It will bring a smile to his face and let him know that even when you're away, you're still thinking about him.