My ex partner is a CG. I too experienced much of what you describe with various disappearing acts and they usually turned out just as Twilight describes, hiding from the collateral damage or going on a spree. During this separation it would not be at all surprising if an elaborate tale is being dreamed up which may then include trying to dump a load of guilt on to you.
I think where love is concerned it is difficult to see the wood through the trees whilst it is covered in the smoke screen of the addiction, if love is there it is hard to detect through the stream of behaviour that would very much give you doubt as to whether it existed – this does not mean that it does not exist but over powered by the addiction which currently the need to gamble is his priority.
If it was me (with much hindsight) I would use this time wisely and learn as much as you can about the addiction and gain the support for yourself. There is little point wondering about what he is up to as you probably already know the answer.
I think the others could well be right, I too suspect he will show himself again ( after finishing in his own mind a shortened version of the Guinness book of excuses!) and you need to be strong for if / when this time comes, so its time to start focusing on what is right and good for you and what you want your own future to be,
It seems a bit contrary as do most things concerning this addiction but expect the unexpected and also gain the knowledge that the unexpected also becomes very predictable with time.
I would think very carefully about what your boundaries will be – should he return
Jenny