I Treat You as a Brother and You Actually Treat Me as My Brother-In-Law

My name is Lu Xingci, and Shen Zhiheng is my brother since childhood. We climbed over walls together, played ball together, got scolded by teachers together, and stayed up all night in Internet cafes together. In the eyes of everyone, we are as good as brothers. I always thought that we would be each other's strongest supporter in this life. Even if we fall in love, get married and have children in the future, we can't break up this friendship. It wasn't until later that I understood—— I regard you as a brother, and you miss my sister. You regard me as a brother, and I also miss you as a sister. They agreed to be brothers for life, but in the end they both wanted to be each other's brother-in-law.