"And Jacob did so. He finished the week with Leah, and then Laban gave him his daughter Rachel to be his wife. Laban gave his servant Bilhah to his daughter Rachel as her attendant. Jacob made love to Rachel also, and his love for Rachel was greater than his love for Leah. And he worked for Laban another seven years." NIV translation
Jacob went along with Laban's plan and, as we see, he did not have to wait the seven years to get Rachel as she was given to him immediately after the bridal week of Leah. You can almost see the trouble coming as this is against the will of God for a man and for a family. The marriage relationship between a man and a woman is a picture of the relationship between Jesus and His people. Our relationship with Him is exclusive and that is how it is supposed to be for a man and his wife. God's wisdom is demonstrated in this as we see that it is not possible for a man to love two wives equally.
Imagine how Leah felt as she saw that her new husband could not wait to marry her sister. That is probably how God feels when we chase after the things of the world even as we proclaim that we love Him.
We also see that Jacob went into debt for Rachel as he was obligated to work for Laban for seven years after he took her to be his wife. This is significant because when you are indebted to someone you are no longer free to listen and follow the Lord wherever He may lead.
"When the Lord saw that Leah was not loved, he enabled her to conceive but Rachel remained childless. Leah became pregnant and gave birth to a son. She named him Reuben, for she said, 'It is because the Lord has seen my misery. Surely my husband will love me now.'" NIV translation
God saw that what Jacob had done was not right and so He allowed Leah to give Jacob his first son. This was significant as the first son was the traditional heir. This is a reminder that God sees all things and that He is in control of all things (even pregnancy).