The phrase "It's everything to me" emphasizes the immense importance and priority of the relationship. It suggests that the connection with the person is the core focus and source of meaning in the speaker's life.
The declaration "you're my world" vividly conveys that the person is not just a part of the speaker's life but the very center of it. It signifies that their love and presence have a profound impact on the speaker's overall well-being and happiness.
In essence, this statement beautifully captures the idea of a deep and all-encompassing love. It reflects the belief that the relationship and the person are the core elements that give purpose and fulfillment to the speaker's life, underscoring their immense value and significance.