My best friend doesn't know what to think or do about his girlfriend's on and off again feelings. Any ideas?

My best friend goes to college about 300 miles away from his girlfriend. They manage to get together about once every 3 weeks or so. She tells him she loves him a lot and oftentimes says she wishes he was there. But sometimes she then says that maybe they need to take a break because she's afraid. She knows he loves her and he's shown it time after time even when she cheated on him once. He is lonely for female companionship and is growing weary of her doubts from time to time. Any ideas of how he should deal with this? What should he do?