1) After reading this book, I learned that love can be very sturdy and true.
2) After finishing this book, I found that love can be very strong and real.
3) After the completion (or after completing this book) of this book, I realized that love can be very solid and genuine.
2008-01-02 03:19:00 補充:
** You use 'ing' with the word 'after' in past tense, because the word 'after' already represents 'the past'. Also, 'after reading the book', that is in the past, it already happened, therefore it should be in past tense as well. hope that helps.