Alternative idea: the author is fucking with us all, and she really literally means she's going to be gone only for the next week. Or some similarly short period of time.
I'd both laugh and be pissed were this the case, but I'd prefer it over the more likely playing this straight because really, leaving it to the last minute to say a long-term goodbye to a good friend is pretty shitty. And it'd be entirely acceptable for one of the other girls to make a move and make it work, and his neighbour has the motivation and courage to do so, and should.