There's an ambiguity in the first verse; one line could be written as "If you want me to, I will" or "If you want me too, I will." The first rendering implies the verb from the previous line ("If you want me to [wait], I will"); the second deals with the reciprocity of the relationship.
The bridge exhibits anaphora:
Love you forever and foreverLove you with all my heartLove you whenever we're togetherLove you when we're apart
The repeated "Love you" at the beginning of each line illustrates both the degree and constancy of the narrator's affection. Additionally, "whenever we're together" and "when we're apart" form a merism.
A second voice comes in during the bridge, and to some degree, this illustrates the entirety of "all" in the line "Love you with all my heart."
There's an added internal rhyme in the line "Your song will fill the air" in the third verse, and this gives something of a sense of that "fill[ing]."
