'We are meant to be' also seems to be a play on words. People say 'it was meant to be!', or 'it just isn't meant to be!', to mean 'it was preordained!' and 'fate has decreed otherwise!' respectively.
In this case, the lyricist has transposed 'it' into 'we'.
'We' here = 'the new entity {you + me}'. So 'we are meant to be' means '{you + me} i