If lying was a necessity for Juliet in Romeo and Juliet, how was it also a bad thing?

Well, Juliet was in a really difficult situation. She was in love (or thought she was in love) with a guy who her parents would NEVER let her marry. In Juliet's mind, it was necessary for her to hide her marriage and lie to her parents in order to be with Romeo. But maybe the story would have turned out differently, less tragically, if Juliet hadn't lied.

One of the most fun things about Romeo...

Well, Juliet was in a really difficult situation. She was in love (or thought she was in love) with a guy who her parents would NEVER let her marry. In Juliet's mind, it was necessary for her to hide her marriage and lie to her parents in order to be with Romeo. But maybe the story would have turned out differently, less tragically, if Juliet hadn't lied.

One of the most fun things about Romeo and Juliet is asking and trying to answer "what if" questions. What would have happened if the star-crossed couple had run away together after getting married? What would have happened if Juliet hadn't refused to marry Paris, thereby angering her father? What would have happened if Romeo and Juliet had not rushed into marriage? After all, they only met each other once; what if they had said, "Let's give this relationship some time?" What if Romeo hadn't killed Tybalt, or if Tybalt hadn't killed Mercutio? What if Juliet hadn't gone along with Friar Lawrence's plan, and instead gone off to Mantua to find Romeo? What your question is asking is, what would have happened if Juliet had informed her parents of her love for Romeo before getting married? Or after? All of the above seem like better decisions than the ones the couple made.

The essence of the story is that Romeo and Juliet were so rash in their love and their marriage (completely ignoring Friar Lawrence's warning, "Wisely and slow; they stumble that run fast") that their lives couldn’t go on normally. One problem piled onto another problem until they were dead. On the other hand, all the decisions they made, including Juliet's decision to lie to her family, were determined by fate, according to Romeo: "Oh, I am fortune's fool!" So no matter what your answers are to the questions above, the conclusion is always, "...but they had to because of fate." Also because the story would not have been very interesting if Romeo and Juliet had made better decisions.