When I arranged Michael Jackson, I really cared about it, and wanted to capture not only the song, or the feeling, but the entire tribute to him.
This piece is my favorite Whitney piece, and really tells the story of the music of that era, and the story of what a woman goes through in her life.
Similar to how Lauryn Hill asks, it hints on how a guy can be after that 'one thing, one thing'.
But this song isn't about being on the defensive when a guy is after "that one thing", it's about wondering. It's about knowing whether something is true and authentic. It's about spending so much time with someone you care about, and the hope that they feel the same way in every single regard.
This is how it's supposed to be -- to find someone so special, that they're literally a mirror of you, and make you a better person all around. So it's more than just the physical intimacy. Simply, they'll make you laugh harder, feel lonely when you're not around, and make you want to change the world.
So that's the answer to the question -- how will you know? Simply because you'll be more than just alone -- you'll be alone, together.