While to an extent I agree with this, it's not just someone but a person he's been in contact with daily for 6 or more months. I wouldn't necessarily write her off either.

Hopefully nothing has happened to her, that is pretty sudden but you act as though you shouldn't be attached to someone just after 6 months. Well 6 months is a short time but a lot can happen in that time when talking to someone daily for an hour at a time! It's not unusual that you're feeling a void and probably missing her. I don't blame you.

I do agree that you should find something to occupy your time that you would have been spending with her talking for now. I hope that it's just something that has kept her from talking to you but after this long I'd give it some time, and try to keep from freaking out too much. If she continues to not contact you, at some point it's true you should just move on.