Leonard's relationship with his mother in step 1 was very close, She was both his mother and his friend and they got along very well.
In step 2 Leonard entered his teenage phase and was no longer as attached to his mother, but nothing too difficult, they still get along well.
Step 3 is when things get complicated, and this is not a very good time in Leonard's life. He starts arguing with his mother when she fought about him smoking, he was already more distant from her.
In step 4 he reconciles with her, becoming close to her again.
Basically.