Lots of really interesting ideas.
As a parent myself, yeah, it's something new, things change, there's nothing like it, it changes you as a person.
The prodigal son angle is interesting. The prodigal son's father indeed gave him wealth - a cup of gold, shall we say. And he left and squandered it, then came crawling back home.
I always heard the "but I left by the back door, and I threw away the key," immediately after the recitation of his father's wealth, as a rejection of his father's worldly things (as well as the father himself, of course). Like, "I don't want any of this."
But framed as the prodigal son narrative, he took the cup of gold and other stuff out the back door. The only thing he threw away was the key.
Of course, either way, the father is God because this is a parable from Jesus to help us understand the ways of God better.
So the key was to heaven (kingdom coming), he threw it away, and carted off the worldly goods.
In the song, we don't hear the part about how he comes back.
So this third verse, a confession of sorts.
Another thought that struck me is the nature of the three verses. Got two ideas about that.
First is the holy trinity. The father, son, and holy spirit. You could read each verse in that lens. Bono has referred to the holy spirit as being feminine, and she seems to be a lover in his songs. So the first verse can be a typical Bono mashing of sex and God.
Second verse is his brother - like him, a son to God. Could be a fellow human or Jesus.
Third is the father.
The other frame is in the three Greek words for love, which occured to me yeaterday as I watched Bono's Meaning of Life interview with Gay Byrne (and there is a LOT to unoack in there, wow). But he mentioned thise three Greek words fir love, and they are:
Eros (and I wrote that in my OP but before I watched that part of the interview). First verse.
Philias, brotherly or friendship love, between equals. Second verse.
Agape, a pure and unconditional love that is often used to describe God's love for us. Third verse doesn't complete the story, but the prodigal son returns in shame to his father's open and joyful arms.