"When Rebekah was told what her older son Esau had said, she sent for her younger son Jacob and said to him, 'Your brother Esau is planning to avenge himself by killing you. Now then, my son, do what I say: Flee at once to my brother Laban in Harran. Stay with him for a while until your brother's fury subsides.'" NIV translation
Rebekah was told about Esau's anger and his plan for vengeance. She immediately planned to save Jacob by sending him away to safety. In this we see that when we try to "help God" with His plan, there can be some bad situations created. They could have trusted in God to fulfill His word to them but instead had taken the matter into their own hands. Now, they were having to deal with the consequences.
"'When your brother is no longer angry with you and forgets what you did to him, I'll send word for you to come back from there. Why should I lose both of you in one day?'" NIV translation
Rebekah knew that Isaac was about to die and was afraid that she would lose all support if Jacob was killed as well.
The plan was to get him out of there until Esau cooled down and forgot about it.
"Then Rebekah said to Isaac, 'I'm disgusted with living because of these Hittite women. If Jacob takes a wife from among the women of this land, from Hittite women like these, my life will not be worth living.'" NIV translation
Rebekah did not have the authority within the family to send Jacob away so she manipulated Isaac to get the job done. We notice that she tells Isaac that it is because of the Hittite women but she never said anything about marriage to Jacob. This reminds us that when you start deceiving people, it usually leads to more and more lying.