I'm kinda torn between answering or leaving this as a comment because it is more like a SR SE post.
In either case, from what I can tell there is little reason for you two to actually hang out in each other's dormitories specifically since all you do is engage in conversations. Inviting into each other's homes specifically might be worse (read: easier to misconstrue) than the coffee shop approach (you'd serve him some coffee for visiting anyway, right?), and you might not want that from what has been described.
With that in mind, I recommend checking out Telegram because Iasking them how they feel about a messenger app and if they use itany since it'd be easier to get in touch with mythe newfound distance. My international friends and SO (contradictinglycontradictorily to the topic enough ), it is both a phone app use Telegram and a web app so you can interact from your home computer as well. It alsoDiscord to stay in touch, which just usesrequire internet so you don't have to worry much about your phone number or charges for voice callsconnection.
Mind you not being physically present with a highly connected interface might boost chattiness, spending your topics to talk about. So I also recommend looking into more planned activities.
These may be digital. Maybe plugging a documentary or whatever movie that you can find on a tube video sharing place like a private cytube channel once a week so you always have something to discuss and talk crap over Telegram voice chat would be fitting enough. And yes, while I also use that with my SO, I also use it with pals from all over the globe and it is always a grand ol' time.