It's a tough situation. Just think about everything Ricks group has been through so far. Could you imagine walking up on another human group during a zombie apocalypse at night? I sure in the hell couldn't. It's a tv show tho, not everything can be explained perfectly.
I personally believe Enid is working with a group on the outside of the walls. Her sneaking into the woods, her dislike for Carl (and I'm sure the rest of the group), and the fact that she seems like a total outcast all lead me to believe she and her group have something planned.