"A month," he repeated - not a question, not really - he believed her, but it still somehow carried a wondering, almost disbelieving sort of tone. Perhaps more concerned. A lot could happen in a month, regardless of how time worked back home versus here. In a month, Thor could have returned, torn the Nine Realms to bits fighting a war that would cost them far too much. In a month, his mother could have been killed trying to lead a war she didn't want to have to fight. In a month, there may be nothing left of the home that was never his and his secrets would all be spilling out without him there to keep them safely contained...
A month was too long.
"Is there truly no way to leave?" The question tumbles out a little more genuinely dismayed than intended, a little more vulnerable than he is entirely comfortable with. He catches it quickly enough, but it's already there - a weakness that, were he on the other end of the conversation, he would have latched onto immediately.