What I get from this is:
She is hoping for the love relationship with this guy to really work out, even though she views it as a hopeless situation.
Because of that, shes looking for signs of "hope" but what she thought was hope was nothing. "Just a paper bag".
Meaning she is losing hope for the future with this man.

One can really understand how much she loves and wants this guy, but there are undercurrents of self sabatage on her part which is all part of her mess.
He's a guy. He just doesnt get her. As usual in many relatiinships.
What ever the issues, she leaves even though she loves him deeply. She thinks she is too much for him.
And he was not man enough to go after her or the love she has for him. If he did he would prove what he is made of. Thereby bringing love and all the hope it needs with him.