You describe intimacy but don't give much information. If there are intimacy issues then you need to address them with him. That may include meeting with a professional together. Intimacy issues can be due to anything including history of trauma, inability to communicate needs, inexperience with a healthy relationship etc. He has to be able to at least acknowledge his lack of intimacy skills. One of the best remedies for such issues is positive communication. You have to work together to develop ways to express your feelings and how to best connect. That connection is different for all couples, but you must learn to have the connection in an emotional and physical way.
You must convey to him that you are concerned in this area and need to work on this either alone or with a professional. Any progress made even small will help. Find self help or professional resources on communication as well. My favorite is Mars and Venus Together Forever. It talks about this in depth.
I think you should especially text while he is away. This maintains a connection that you don't have at home. This adds to the romance of having this connection. You can even say things this way that you or him may find embarrassing or uncomfortable if facing each other. You can take a risk by these means.
You have to communicate more effectively and that just takes more effort. You have to do this together. If he shuts down then you can't fix this alone. You have to be able to state their is a problem and agree to work on it. He has to be equally as committed. If he isn't nothing will change. So start by having a talk at a very personal level and see what you both are willing to try and how much of a commitment you have to each other.
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I think it is great that you are doing all this work and feel healthier than before. I understand your desire to help your boyfriend out to resolve his own issues, after all you can empathize with his codependency issues. The problem I see is that you changed and you are healthier now but he may not be healthier. You want to help him out but to him it may feel like you are pushing too much. Just imagine that you are running a race and someone is trying to push you hard up the hill. The person who is pushing you will feel resentful and they person you are pushing will feel like they can't do anything right, they are not moving fast enough. He will be afraid he will disappoint you and feel pressured. I also wonder if you boyfriend is suffering from a bit more than codependency an attachment disorder. Adults with attachment issues run away from relationships when the relationship gets to close for comfort. I understand not wanting to give up on your relationship but relationships take two people. The best thing you can you do now is give him the space to figure some of those things out. If you need to say your peace meet with him and tell him how you feel. Telling him what the problem is with him may turn him off to you and he may see you as controlling. I am not telling you what to do but I just want to bring up all the possibilities. I understand wanting closure but I think you should talk more about how you feel about his behavior. If he wants feedback you can say that you think that he should look into codependency and seek counseling. My feeling is that the is not ready to hear this now but eventually he may ask you what you think went wrong. I think this person may have been the right person for you a year ago but now that you are healthier you may need to move on and leave him behind. He may be a great guy but he does not seam to be ready to work on his issues.