You don't know that. I've got different types of intimate relationships going on with several people and they all have some level of commitment. I'm not going to marry all of them or live with all of them, but those are not the only metrics of commitment. Each of these relationships is different, has its own elements to it, different time commitments, etc., but they are all important to me - as I am to them.

Just because you don't understand something doesn't automatically invalidate it.