Refletions on Gravity and Gratitude

You can’t stop yourself from loving someone you shouldn’t but you can’t force yourself to love someone you’re better off with.

I got that phrase from here, at the The Bulleted Something ( a blog which I am kind of jealous of because I feel as though I should have come up with that first).
Why is it that as humans we are constantly tempted and lured by what we want but cannot have?
Why do we overlook what we get freely?
I have to wonder.
There are countless posts about me and Babes. Things of the past. A relationship that will never end: my best friend. The one who finishes my sentences and my jokes, the one who can comfort me, and ease me, the one who can soothe and relax me. The one who feeds off of my energy, who knows how to make me smile and whom I share so many memories with. He is -as of right now- the one man I trust. After knowing him for so long, and know how he and I share an indescribable bond, I am utterly open with him; I am vulnerable and sensitive and I believe he wishes no harm.
But as much as I love him, and believe me when I say I do; I can't force my curiosity out of me. I can't get these thoughts out of my head of wondering what else is out there, who else roams this world and what they are like, I can't stop asking myself if there is anyone in this world I could learn to trust and I could share a similar bond with.
Why is this? Why are we humans genetically encoded to not be content and satisfied with the things we already have in our head and hearts? Wouldn't we all be happier if we could learn to be that way?
Makes me think of John Mayer's song "Gravity". Here are the snippets that apply to this post:

"I'll never know what makes this man
with all the love that his heart could stand
dream of ways just to throw it all away"

"Twice as much, ain't twice as good
and can't sustain what one half could
It's wanting more that's going to send me
to my knees"

Well folks, this is my queue. Just remember to be content and grateful with the many blessings you already have. I'm learning to do the same with mine.