T, read through Blu's thread again and don't you dare beat yourself up. This is not because you are bad at DB or anything you did over the last couple of months. I want to hear you say aloud ten times right now "I did not cause this. This is not my fault." She said she was a terrible DBer and doesn't think that is why he came back.
In the end, I think whether they come back has more to do with them internally and the random chance of how and when things happen for them.
To get your mind off all of this and to remind yourself that very little in life is a result of careful planning and execution, read the Malcolm Gladwell book The Tipping Point.
