No Love After Separation

There are trees in the mountains, and the trees have branches. My heart is happy for you, but you don't know it. Since childhood, Mu Wan has been like a shadow, following Li Bai Hanyu like a dog-skin plaster, accompanying him all spring, summer, autumn and winter, and watching him fall in love with other girls. Okay, these are all bearable, but why did you let me help you pursue my sister, and also helped her hurt me? In the end, you two stayed together, and who am I?