How do the three stages brother transitions through during the story relate to the theme?

The three stages I see as a reader include
these:

1. Love: In the
beginning I saw a brother motivated to help his learn to be more than he was. This love
may have been selfish because all boys want someone to play with.
 

2. Cruel Pride: It seems
that every time Doodle achieved much more than would have been expected from him, it was
not enough. When the experts though he would never move and Doodle crawled, brother
wanted him to walk. This stage continued all the way until he abandoned Doodle in the
rain on that last day. We see this concept exemplified in the
quote:

There
is inside me (and with sadness I have seen it in others) a knot of cruelty borne by the
stream of love.

3.
Guilt: I think the purpose of the story is to show the
guilt the author felt for abandoning his brother, one who was less capable of handling
himself than the average person.

I see these stages connect
the the theme of the conflict between love and pride. Doodle's brother wanted to love
him all the time, but it was a burden to bear all of the effort that it took to ensure
that Doodle acquired skills necessary for life. The one day that brother abandoned
Doodle after getting fed up with helping so much was the day that he needed the most
help.