因为你是唯一所以我想珍惜
[yīn wéi nĭ shì wéi yī suŏ yĭ wŏ xiăng zhēn xī]
'Because you are the only one, I want to cherish' suggests the uniqueness and irreplaceability of the person being addressed. The author wants to show their love and care because they think of this person as irreplaceable.