I had the same problem with the same side. I accidentally rolled (about 1mph) into a snow mound when I lived up north and I heard something "crack" in the bumper. Once the snow melted and I had a chance to inspect what happened, I noticed a gap just below the passenger side headlight -just like yours.
Once the weather warmed up, I removed the front bumper and saw that the corner of the mount broke off, along with the whole piece completely breaking away from inside of the bumper. The metal tab on the frame was the only thing holding it on. Anyhow, I used a fiberglass repair kit (with the fiberglass cloth) to reinforce the mount to the inside and creating a new corner. I clamped the mount to the inside of the bumper, then applied the cloth and epoxy with a brush. It wasn't pretty when finished, but it definitely was effective.
I did the repair in the spring of '13 and it's still holding strong today. The repair even withstood the long ride going through pothole-ridden Philly, Baltimore and Washington DC when I drove it down here to FL last November.