You see that person. Be it boy, girl, other, or whatever your flavor is. And you know, you just know that you could walk up to this person and lay the greatest, never ending, completely mind blowing kiss on them. When a full lifetime of blissful possibilities are transmitted with a quick meeting of the eyes. Souls brushing together for an instant, to create a feeling of unity in this world of complete separation. All it takes is that one second, that bubbling feeling at the bottom of your heart that works its way up to the top and begins to spill out onto your face. Everyone gets this feeling. It's probably just chemicals, you know it is, but it's so great that you can't make yourself care. You know that it doesn't matter. You can even imagine an entire life with this person, all in the span of a few seconds; the first date, meet the parents, the proposal, marriage, buying a house, kids, the mini-van, sending the kids off the college, together. It's heaven in a second.
Suddenly, those eyes your staring into don't look so dreamy anymore, they aren't grasping your soul as you thought. You realize that she was not even looking at you, she was trying to see the clock that was behind you. All the while cursing you for being an idiot for standing there staring like a goof when all she really wanted was for you to move. You've just made the realization that it was completely one sided. You have just been crushed.