Has he gone back to Amsterdam?
You know, a relationship with an addict is nothing like a relationship with a non-addicted person.
The addict's first love is their drug of choice. It is a very self-centered type of life. Their first job/love is always the drug, finding it, using it then finding some more.
It's virtually impossible to hold up any kind of relationship under those circumstances.
He wants distance, I assume you are still broken up? I would surely back away from this.
Things like not being able to meet your Father and his wife, well things like that happen right? It's not that big a deal in the great scheme of things. Have you considered that getting right out of this relationship and taking care of yourself and letting him have his space might be the best thing for you?
I suspect his usage, based on what you have described is probably much more than you are aware of.