I think I'm falling out of love?!

I'm in a long distance relationship. This is our 2nd year together. Currently I no longer feel the passion or the urge to talk to him daily. I used to wait for his text and his call like crazy. I used to need to know everything about his day. I used to go nuts if we don't talk a day. We used to talk for hours. Now I don't feel any of that. I don't care if he texts or doesn't. It doesn't make a difference to me and I don't feel anything. I feel plain.

Is this how falling out of love feels? Is this something else? Is this the effect of distance?