Hi Eheuer, and welcome to the forum.
I'm sorry you're feeling this way. There's always a lot of insecurity in our lives when we're in love with an addict, and I wonder if his not contacting you has somehow brought that insecurity to the surface.
It sounds like you want someone to tell you that it's normal to go off the radar while in rehab. I don't know. I suspect different rehabs handle it differently.
But I need him too and I feel like I've been abandoned.
This quote concerns me. Is it possible that you may be a bit too attached to your boyfriend? He's very sick right now, and it sounds like he's made the hard choice to get healthy. That's going to take 100% of his energy for the foreseeable future.
Maybe, while he's working on himself, this would be a good time for you to work on yourself as well. Educate yourself on addiction. Read some of the stickies at the top of the Family and Friends forum page. Read some of the posts on the Alcoholics forum page as well. Check out an Alanon meeting in your local area. And of course, keep reading and posting here.
((((((( hugs ))))))