1) Adam and Eve
When God created Eve and presented her to Adam, Adam exclaimed: "This time, bone of my bones and flesh of my flesh! This one shall be called 'woman,' for she was taken from man" (Genesis 2:23. Spontaneously saying "this time," he expressed his delight and emotional arousal -- his love at first sight -- for his newfound mate.
2) Rebecca and Isaac
Before Rebecca even saw Isaac, she had agreed, with devotion and self-sacrifice, to be betrothed to him. On her way to meet him, she saw a man approaching in the field and knew intuitively that it must be him. She experienced such intense emotions of love at her first sight of him that she nearly fell off her camel. By virtue of having so completely bound herself to him beforehand, her soul was able to recognize (know) him as her true soul mate even before they had formally met.
3) Jacob and Rachel
In Kabbalah, the couple that more than any other personifies the love between GoIsrael -- and exemplifies, as well, the ideal state of manifest love between husband and wife -- is Jacob and Rachel, whose relationship is also the Torah's prototypical example of romantic love.
Like Isaac, Jacob knew that he was going to marry his relative's daughter. When he arrived at the well near Haran, the shepherds told him that the approaching maiden was Rachel, his uncle Laban's daughter. His love at first sight enabled him to single-handedly roll back the boulder covering the well at which the shepherds watered their flocks, in order to let Rachel's flocks drink. And he cried, for he sensed that he would not merit to be buried with her (Rashi on Genesis 29:11 and that there would be difficulties and delays before they could marry.
However, his da'at was not complete enough to be immune to deception. He knew only that he was coming to marry one of Laban's daughters; since he did not know which, his psychological preparation was conditional. Therefore Laban was able to deceive him by giving him Leah first, in place of Rachel. Despite the intensity of his love for Rachel, on his wedding night he did notknow whom he was marrying.
In both of these cases (2 and 3), the parties were psychologically prepared to meet their soul mates, so events proceeded relatively smoothly. Psychological preparation for an event serves as a mental "guard" or protective shield, which controls and directs the intense emotions of the heart.