Questions regarding the Harrycrux

[terri-testing.livejournal.com]

“While the magical container is still intact, the bit of soul inside it can flit in and out of someone if they get too close to the object. I don’t mean holding it for too long…. I mean close emotionally…. You’re in trouble if you get too fond of or dependent on the Horcrux.”

(Hermione regurgitating Dumbledore’s books, DH p. 103)

So why were Hermione, and Ron, and Hagrid, and Mrs. Weasley, never “in trouble”?

Why was the Harrycrux not subject to that particular effect?

And how did Dumbledore know it wouldn’t be?
( In theory )