There are several synonyms that can be used to express the sentiment of "I love you truly." Some common alternatives include "I adore you," "I cherish you," "I am devoted to you," "I am smitten with you," and "I am infatuated with you." Other options could include "I love you deeply," "I am enamored with you," or "I am captivated by you." Ultimately, the chosen synonyms will depend on personal preference and the tone that one is aiming to convey. Whether it's a romantic gesture or simply an expression of affection, using different synonyms can add depth and meaning to the sentiment of "I love you truly".