New to this

Greetings!

A few months ago I found myself positively swept off my feet by a man I'd known through business for awhile.  On our first date he mentioned he has ADHD and is treating it.  Not much more was said, so I started doing research on what that can mean.  I realized pretty quickly he was in hyperfocus and tried not to get attached to the idea that this level of attentiveness would be ongoing.  Sure enough it waned, no big deal however he seems to be getting progressively less communicative. 

One of the other things he mentioned early on was that he has "abandonment issues" so he gets worried if he doesn't hear from me regularly.  Okay, I made it a point to text or call him frequently and he'd do the same.  Lately though he doesn't contact me at all unless I contact him.  I realize he works and has a son (who is with him every other weekend) but I'm getting a bit weary of having to initiate every contact.  He's gone on a business trip this week and I know he won't contact me at all.  I'm trying to pretend that Seattle is on the moon thus no phone service so I won't take it personally, but I don't know.  The last trip he went on he didn't contact me at all and when he got back he called and started chattering away like nothing was awry.

I guess what I'm trying to figure out is if this distancing is normal guy needing space stuff and I should just hang tight and see if he comes back or if it is a function of ADHD.  Saying "oh its the ADHD and he is just too buys focusing on blahblahblah" starts to feel like a thin excuse for not wanting to face the fact that he may be moving on.  Then again given his history of reappearing like nothing is wrong I just don't know how to go about this.  When it is good it is very very good, but when it is bad it is horrid. :)

Any advice would be most appreciated.