I think I originally asked myself this question several years ago when I saw a meme in regards to 'what the signs want to hear' and the three options were: I want you, I need you and I love you.
My sign, Scorpio, got 'I want you'. At the time, I felt it wasn't correct. I would want someone to tell me that they needed me, particularly in a relationship.
You see, I saw needing someone, as stronger than a mere want. It's something that the person has no control over. Being with someone is not something they debate over in their head, but instead is a fact that they require this person in order to be them, or to be whole. I viewed needing someone as a solid, shall we say.
Wanting someone on the other hand is a choice. They can live without this person but they choose not to. And that's lovely, but like all choices, decisions can change. So do preferences. And I saw this as not a solid, but a flowing liquid with a current that can alter at any second. A lot like my mind.
It wasn't until recently that I realized that needing someone might not be as particularly strong as I had once thought. Now I agree with that meme that for some unknown reason, still haunts me until this day. To have someone say they want me, that they thought about it, debated it over within their head, doesn't need me in their life but prefers me in it anyway, is what I would want to hear.
As opposed to needing someone, it's powerful, and strong, but what happens when you don't need them anymore? Or they don't need you?
What if they found that missing piece, in themselves perhaps, or a pet or even a new food, and that need they had for you to keep them together is gone? That can change things quicker than a change of mind. And the realization that you served your purpose and are no longer required, can hurt like a motherfucker.
But I guess the two common reasons of being with someone: because you need them or want them, is both flawed.
Maybe there's a path leading from the two that meets them halfway. And maybe that middle ground is what they call love.