Rachel and Leah are types of the Church and Israel because of God's love for the Church more than the Jews (Gen 29:30), the realization of which will be seen in the millennium (Eph. 2:6-7; Lk. 7:28; Psalm 45:14; Gal. 4:24-26).
bold emphases mine
ESV Gen 29:30 So Jacob went in to Rachel also, and he loved Rachel more than Leah, and served Laban for another seven years.
ESV Eph 2:6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus,
ESV Eph 2:7 so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus.
ESV Luke 7:28 I tell you, among those born of women none is greater than John. Yet the one who is least in the kingdom of God is greater than he.”
ESV Ps 45:14 In many-colored robes she is led to the king, with her [the Church's] virgin companions [the Jews] following behind her [cf. Mt. 25:1-13].
ESV Gal 4:24 Now this may be interpreted allegorically: these women are two covenants. One is from Mount Sinai, bearing children for slavery; she is Hagar.
ESV Gal 4:25 Now Hagar is Mount Sinai in Arabia; she corresponds to the present Jerusalem, for she is in slavery with her children [the Jews].
ESV Gal 4:26 But the Jerusalem above is free, and she is our mother.
Rachel and Leah's jealousy are also types of the Church and Israel (Gen. 30:1; Rom. 10:19; 11:11). "through their trespass salvation has come to the Gentiles, so as to make Israel jealous" (Rom. 11:11, ESV).
Can it be said, that God desired the fruits without the law (Rachel), but had to undergo the Mosaic law (Leah) first?
Genesis 29:31-35 ESV, bold emphasis mine
15Then Laban said to Jacob, “Because you are my kinsman, should you therefore serve me for nothing? Tell me, what shall your wages be?” 16Now Laban had two daughters. The name of the older was Leah, and the name of the younger was Rachel. 17Leah's eyes were weak, but Rachel was beautiful in form and appearance. 18Jacob loved Rachel. And he said, “I will serve you seven years for your younger daughter Rachel.” 19Laban said, “It is better that I give her to you than that I should give her to any other man; stay with me.” 20So Jacob served seven years for Rachel, and they seemed to him but a few days because of the love he had for her. 21Then Jacob said to Laban, “Give me my wife that I may go in to her, for my time is completed.” 22So Laban gathered together all the people of the place and made a feast. 23But in the evening he took his daughter Leah and brought her to Jacob, and he went in to her. 24(Laban gave his female servant Zilpah to his daughter Leah to be her servant.) 25And in the morning, behold, it was Leah! And Jacob said to Laban, “What is this you have done to me? Did I not serve with you for Rachel? Why then have you deceived me?” 26Laban said, “It is not so done in our country, to give the younger before the firstborn. 27Complete the week of this one, and we will give you the other also in return for serving me another seven years.” 28Jacob did so, and completed her week. Then Laban gave him his daughter Rachel to be his wife. 29(Laban gave his female servant Bilhah to his daughter Rachel to be her servant.) 30So Jacob went in to Rachel also, and he loved Rachel more than Leah, and served Laban for another seven years. 31When the LORD saw that Leah was hated, he opened her womb, but Rachel was barren [Rachel, the Church, was barren first]. 32And Leah conceived and bore a son, and she called his name Reuben, for she said, “Because the LORD has looked upon my affliction; for now my husband will love me.” 33She conceived again and bore a son, and said, “Because the LORD has heard that I am hated, he has given me this son also.” And she called his name Simeon. 34Again she conceived and bore a son, and said, “Now this time my husband will be attached to me, because I have borne him three sons.” Therefore his name was called Levi. 35And she conceived again and bore a son, and said, “This time I will praise the LORD.” Therefore she called his name Judah. Then she ceased bearing.
(For such a dogma to be taught, the answer must first be asked: where would it specifically say in scripture that God didn't desire the law at first?)