well, the "something borrowed, something blue" phrase is obviously referring to the wedding tradition. i think it's repeated because their love has become repetitive and like a tradition rather than exciting and new. he's coming to the point where he is realizing that, although his life "begins and ends" with her (she is all he can remember in his life), it's not going to work. he has to, and NEEDS to, leave her "on the interstate."
well, the "something borrowed, something blue" phrase is obviously referring to the wedding tradition. i think it's repeated because their love has become repetitive and like a tradition rather than exciting and new. he's coming to the point where he is realizing that, although his life "begins and ends" with her (she is all he can remember in his life), it's not going to work. he has to, and NEEDS to, leave her "on the interstate."