Although it has taken on a strictly romantic revision of meaning in some modern decks, traditionally the Lovers card of Tarot reflected the challenges of choosing a partner. At a crossroads, one cannot take both paths. The images on this card in different decks have varied more than most, because we have had so many ways of looking at sex and relationships across cultures and centuries.
Classically, the energy of this card reminded us of the real challenges posed by romantic relationships, with the protagonist often shown in the act of making an either-or choice. To partake of a higher ideal often requires sacrificing the lesser option. The path of pleasure eventually leads to distraction from spiritual growth. The gratification of the personality eventually gives way to a call from spirit as the soul matures.
Modern decks tend to portray the feeling of romantic love with this card, showing Adam and Eve at the gates of Eden when everything was still perfect. This interpretation portrays humanity before the Fall, and can be thought to imply a different sort of choice -- the choice of evolution over perfection, or the choice of personal growth through relationship -- instead of a fantasy where everything falls into place perfectly and is taken care of without effort.
The Fool comes to a cross-roads, filled with energy, confidence and purpose, knowing exactly where he wants to go and what he wants to do. And comes to a dead stop. A flowering tree marks the path he wants to take, the one he's been planning on taking. But standing before a fruit tree marking the other path is a woman. He's met and had relationships with women before, some far more beautiful and alluring. But she is different. Seeing her, he feels as though he's just been shot in the heart with cupid's arrow, so shocking, so painful is his "recognition" of her. As he speaks with her, the feeling intensifies; like finding a missing part of himself, a part he's been searching for his life long. It is clear that she feels the same about him. They finish each others sentences, think the same thoughts. It is as if an Angel above had introduced their souls to each other. Though it was his plan to follow the path of the flowering tree, and though it will cause some trouble for him to bring this woman with him, to go somewhere else entirely, the Fool knows he dare not leave her behind. Like the fruit tree, she will fulfill him. No matter how divergent from his original intent, she is his future. He chooses her, and together they head down a whole new road.