I've been pondering this for a second, but I have this theory that ghosts can feel other ghosts, and the show kind of has this emphasis on kissing. Such as Charles misses kissing, and Edwin never got to experience his first kiss before he died. Now, technically, Edwin had his first kiss with Monty and Charles kisses Crystal, but they can't feel it physically. I don't know. I just feel like it's set up to be really beautiful if Edwin and Charles ever do kiss.