Solo diving can have hidden risks leading to fatality. I teach the PADI self-reliant (read: solo) diving course, but I rarely do it myself, because my wife would kill me if she knew.
My fiancee is really freaked out whenever I dive solo. She'd kill me if I died diving. She just wants a text when I'm out of the water. That works for me. If I switch to a rebreather, then the solo diving will be put on hold for a quite a while.