What does your boyfriend mean by sending this?

If your boyfriend often sends such pictures, it means that this is just his personal hobby. He likes natural beauty, is close to mountains and rivers, and feels life. But if it's a sudden change, it's completely different from before, and your feelings are right. As his girlfriend, it shows that you love him very much, and your heart has been vibrating at the same frequency with him. You can take the initiative to ask him to further observe whether anything has happened. Let him feel your love and wish you happiness.