Sometimes you don't need any reason to like someone. When Mumu started to lose weight for Lin Yu, it was already destined that Lin Yu would return the lost weight to her in the future of their lives.
Yang Lin fell in love with Lin Yu and started clamoring to lose weight for him from the first time they met; from the first time he learned that his name also had the word "Lin" in it, he persistently believed that the two were a match made in heaven.
Chen Mobai has been in love with Yang Lin since he was in elementary school, just like his name, silently without expressing his love until he grew old.