it was not obi-wans fault. qui-gon was supposed to die that day so that obi-wan would train anakin and anakin was supposed to fall. and obi tried to stop it but he couldnt. it was anakins fault he looked at obiwan as a father not as his master or teacher. shmi dieing was a big push towards darkness and sidious manipulating things didnt help. i think that the froce wanted this to happen, it wanted the jedi to be destroyed because they had become stagnant and had forgotten about their real duty. they had become pawns of the senate they werent wut the force wanted them to be so it destroyed them and made them stronger.