Hi Jess-
My guy moved in FAST too - told me everything, fell in love, lots of texting, calling, promises made, trips planned, etc. etc. but when things started getting really REAL in our relationship to the point of him seriously considering selling his house and moving in with me, etc etc (after 6 months), surprise surprise, he broke up with me (the 1st time - unfortunately, not the last).
Sorry - I shouldn't say it so sarcastically but seriously, in hindsight, if I had paid more attention, I would have seen the signs.
Basically, a guy (or girl) who moves FAST, falls FAST, everything FAST FAST FAST and NOW NOW NOW and whirlwind...well, FAST does not LAST. It is just how intimacy works (or doesn't work, rather). You have to get to know each other first and that can only be done over TIME and no, I don't mean 3 days of 24 hours straight together. (That's how I always tried to "work around" my own intuition - I'd use all kinds of excuses).
So, who knows what is going on with your guy. Maybe he moved in too fast and is having "buyer's remorse" so to speak. Or maybe he is doing this same thing to 2 or 3 other gals at the same time as you. Or maybe he's just the run of the mill "messed up puppy" who doesn't know his head from his ___.
You can't control anything else but yourself and what YOU decide is acceptable for you. Set your own boundaries and communicate them clearly. If you are not okay with no communication for a certain amount of time (whatever that amount of time is - it's your call), tell him. Example, "I need to hear from you once a day (once a week/once a month - whatever you feel you need) or I really cannot maintain contact with you for my own mental wellness." (Or something like that)
If you are in a serious, committed relationship, the once a day rule should really not be that big a stretch. After all, a text takes like 5 seconds to send and ta da, he's done with his "quota" for the day, right?
If, however, he's struggling with does he really even want a relationship, etc. etc., then maybe once a week or even once a month might be more appropriate. Just a thought.