Chasing pavements:
i think this song is describing what is like a walk of love, like a walk of life. she loves this guy, but she's a crossroads of her life; should she chase after him, and see where the relationship goes, or end it? like in the line "should i give up or should i just kept chasing pavements, even if leads nowhere". i think that in this song, she's just describing her dilemma, should she continue to fall in love with this guy, even if it ends?
To me chasing pavements is metaphorical for going after a dream or a possibilty and holding onto a thought, feeling regardless of how hopeless it may seems. a bit like a wild goose chase.
I agree with the unrequited love idea too.