This simple yet powerful statement conveys the all-encompassing nature of someone's thoughts and feelings for another person. It suggests that the individual is constantly preoccupied with thoughts of the person they love.
The phrase "All I do is think of you" underscores the idea that the person is always on their mind, occupying a central and continuous presence in their thoughts and emotions.
In essence, this quote is a declaration of deep affection and longing, emphasizing the significant impact and importance of the person in the speaker's life. It beautifully captures the all-consuming nature of love and the way it can dominate one's thoughts and feelings.