"
I know that goodbye means nothing at all
Comes back and begs me to catch her every time she falls
It means she uses him as a her lifeboat. She tells him it's over, that she no longer wants him, but as soon as she starts to face problems out there, she comes back to receive his love and support. She isn't interested in him for who he is, she just wants to hold onto him, because she's too insecure to deal with her problems alone.