Back in June, I posted my take on commitment in another thread:
Originally Posted by nycindie
... when I think of the word "commitment" I think of people aligning themselves toward the same goal. Basically, it's like a contract or agreement, and the commitment will mean whatever the people involved want it to mean, depending on what they're committing to.
They can be in an open relationship and committed to honesty and safer sex; they can be poly-fi and committed to being faithful to each other; they can be monogamous and committed to growing old together. Of course, these are just a few scenarios off the top of my head, but you get the idea. It can be any combination of whatever the people want. But I do think progression toward deeper understanding and knowledge of each other, and self-growth, is a part of being committed.
I think that, simply, the act of committing to/with someone is a form of allegiance and a promise to work toward something and support each other in that endeavor.
I should add that, of course, commitment is definitely much more than a promise. The important part of the contract is following through on your commitment and doing what you say you are committed to do.
As far as who you make commitments with, and how you choose the people you want to commit to, I think it naturally comes out of the discovery of mutual desires and goals. When people are in sync with what they want (which may or may not be the same thing but could just fit together very nicely), a commitment flows out of that alignment with each other. And sometimes the commitments are unspoken but clearly understood.