Needs are constant. They don't change over time. I need food, I need sleep, I need my daily diet Dr. Pepper. Desires ar e variable. Today I long for cr me-filled donuts, tomorrow I'll crave chocolate.
Desire depends on change of heart.
When it comes to dating, I am all about the whimsy of wanting. Last summer, all I wanted was a Cute Boy. I wanted someone with a beautiful face to kiss, soulful eyes to stare into, a hot body to lust after. In the fall, I wanted to be taken out and fawned over. I wanted attention and money lavished on me.