You can't get him off the phone talking with his friends,
but all he gives you is one- and two word answers.
Your house is a motel where he eats and sleeps,
but he never shares, never opens up.
And when you think about it, honestly, why should he,
if every time he does open up his soft underbelly,
you elephant stomp it with autobiographical advice and " I told you so's."

Andからがわかりません　why should heの続きはopen up his soft under belly
ですか？　when you think about it のitは何をさしますか？

構文がいまいちつかめません　解説お願いします

7 habits of highly effective peopleからの出典です

himは作者の息子です