Divorce me, untie, or break that knot again, (line 11)
The "again" might refer to that other major moment when God needed to untie people and break their knot: when he banishes Adam and Eve from the Garden of Eden for eating from the Tree of Knowledge.
Take me to you, imprison me, for I, Except you enthrall me, never shall be free, Nor ever chaste, except you ravish me. (lines 12-14)
Check out the "Detailed Summary" and the second "Quote" in this section for more on this, but remember that in many branches of Christianity, suffering in life is a key step for getting into Heaven. This all comes from the Bible, and especially the passage: "Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit. He that loveth his life shall lose it; and he that hateth his life in this world shall keep it unto life eternal." (John 12:24-25).