My take on this that its about a one sided love and most likely the other person doesn't know or at least realize the depth of that love. Much like a guy and gal who are "friends". The depth of the love is express in what they'll give up for the other person, a flying machine, humility by letting that person go where there heart desire with out putting up any fuss and yet waiting (in the rain if necessary), still wishing them well - of course since their just "friends" - their "no supposed to care"