So you moved internationally and had tell friends/family/etc., as well as government agencies, movers, blah blah blah?
Yes, especially the blah blah part 
And Lucas moved, like, down the hall to another apartment?
Yes Or to somewhere close, where not as much stuff needed updating and most people with whom he interacted outside of that wouldn't care or need to know?
Yes********SPOILER********
After breaking up with his girlfriend, my friend Lucas moved to a smaller apartment within the same apartment building. Half a year later, he and his new girlfriend moved into a bigger apartment in, you guessed it, the same building. So his postal address never changed and he didn't have to update it anywhere. I moved from Germany to the Netherlands, so I gave my new address to friends and family, but also had to let the tax office, government, insurance companies etc. know about it.Thanks for playing, everyone!