After a while, Tom couldn't remember where he left the book.
Why did he not think about remembering it?
Tom was the kind of guy who left everything behind
It's easy to forget things sometimes, but if it's always happening that isn't healthy for him or his books. He needs to get some help because he may have a disorder or disease that lowers his memory capabilities.
Tom is happy.
It is great that he is happy but I do think that he needs to be a little more responsible with his belongings. He should try not to misplace his books anymore.