Here are a few sentences from a friend which are very very apt at describing the situation
On my ex using me as an emotional crutch with problems with her current beau
“She needs a pillow to cry on. You are the pillow on which she sleeps on…with another guy”
On his being over cautious when taking certain decisions
“Sometimes the weight of the armor causes me to fall without anybody attacking”
I could not have come up with better analogies than this if I had to try.