Considering my take on people -how complicated and , in many ways,unfathomable we are,my answer to most of these questions is,I have no idea.
At this stage,I have only two observations.
I bet her affairs were stressful to mahler and may have adversely affected his health.
On the other hand,I,for one,am grateful that,having heard the BBC tape of the 10th,she gave her permission for M10 to be performed. Thus,in a sense, we were given the wonderful experiences that M10 can offer. Hopefully she realised that the world had another Mahler masterpiece;even,perhaps,that she owed it to the world to relent. Good call !! to say the least.
Ivor