Where has she gone?

Nala the cat has left. She has been gone for seven hours, which may be nothing for many cats, but for Nala, who does not really like to go out at all without us, it is ages. We were in the garden with her in the morning, then she vomited (she often does this), so when I went in I closed the patio door so that she would not come back in and vomit again inside. We were only in the room with the patio window, so she could see us if she stayed there, and I opened the door again after about 45 minutes. But at some point she left, and has not come back. I think that may be it