His wedding ring is always on when he goes into the dream world, it's off when he's in the real world. This leaves only one conclusion that at the end, when he's supposed to be awake, he is actually awake, and because he doesn't have his wedding ring on.
Mal was his totem, when she was around, he knew he was dreaming, when she wasn't, he was awake. When she was around he was married to her. When she wasn't, he didn't wear the ring.