All well and good, but it doesn't really answer the topic. Is there a final cut off for accepting this? If so, why? Why would a being that is goodness and love give up on certain souls for all eternity? Such an act makes the attributes of goodness and love meaningless, many human parents don't even ever give up on their loved ones.
We cannot know so we cannot “give up”, but God could know when a person reaches the point at which they will never change, everything possible has been done that could cause that person to accept God’s help, but they will never do it. You could say: “If God puts a gun to their head than they will be willing to accept His help”, but God is offering pure charity of Love and if you do not accept His charity as pure charity, you will not be getting the Charity (Love).
Look at the story of the Rich man and Lazarus (Luke 16:19-31), here you have at great person cost to God a rich man provided with the very best opportunity to experience pure Godly type Love with Lazarus being tripped over every day. The Rich man never ceases this easy opportunity, so what better opportunity could God provide?
You “assume” that God is at fault in some way because a mature adult has repeatedly refused God’s Charity (Love) and thus would accept it under some other conditions? But God has set up every individual that will reach maturity with the best opportunity for them to accept His charity. God cannot force them to accept it or it would not be Love.