Su Lio's body is like this, she could die at any time, it's impossible for her to get married or engage in romantic affairs, and as long as Grandpa is around, he would never approve of Su Lio and his affairs, even though they have no blood relationship.
This is just one reason. Ma Han, his father, would also never agree, and no one in the family would support such a 'forbidden' love. Su Tong knows this, and that's why he keeps his feelings hidden, never revealing them. Usually, he treats Su Lio well as her brother, protecting her, never allowing her to suffer even a little injustice, and whenever someone bullies her, Su Tong gets furious.
