I don't understand what obi-wan did wrong. everything he did was logical he did not ask anikan for help because he did not need it, at the time he did not know that it was a trap let alone a trap made by 2 sith. He slipped in and got her out so easily if maul had not been there and waiting they would have gotten away no problem. No amount of groveling on obi-wan's part would have stopped maul from killing her. maul killed her simply to hurt obi.
I will now unfairly contrast this to malgus