I’m not a moral theologian and I’m not a spiritual director. But as somebody who in the past felt massively let down by God, I will say how I was able to move past it.
First, I had to be honest with God. I was mad at Him and I told Him so.
Second, I followed the typical relationship rules that you focus on the what action hurt you, and not the person you’re mad at. So it looks like this—“I felt let down when you xxx…” as opposed to calling names.
Also, I tried to learn everything I could about Him—just like how in any relationship, you take the time to learn who you are dealing with.
And then (and this is the hardest to explain), I had to “forgive” God, ie let go of my anger towards Him. Anger can be very toxic and corrosive under certain circumstances, and I decided that’s how it was for me.
Something that really helped me to get to this point was the rememberance that God incarnated, became one of us, and suffered everything we do. It didn’t explain the mystery of suffering, but it was an additional insight.
Also, learning to give thanks for something, anything, every day helped me jump start my spiritual life in ways I couldn’t have predicted.

ray:t2: For you!