The song to me means. What she feels for him no matter what he has done to her she still loves him. No matter how hard hes been on her or hwat he does when hes away she still longs for him, when it say "But I can't move on,.
Cause that means forgetting, forgetting everything we've had, " she can't move on after all they have been through and she doesn't want what shes been through to go to waste so she is willing to hold on to her life basicly.