SillyAli18,
I read your story and can see this is CLEARLY a very distressing situation for you and can understand why. I wish I could give you a short answer

. I can't seem to ever have a short posting and I'm sure I repeat myself all the time, so for that I apologize.
You and your boyfriend lived together, seem to have had an intimate relationship and he HAS opened up a lot to you which means a lot.
So, here are some of the best guesses I can come up with as to what might be going on:
1. He requires a lot of time alone at certain times and can't deal with anything (even returning phone calls) during these periods of time. When I get stressed I become more and more avoidant. I don't even communicate with people I like and care about, just because I can't deal with ANYTHING because there is too much going on in my life or in my head for me to cope with - and it's NOT personal in anyway. Going back to stressors: They really trigger my avoidancy - BIG LIFE CHANGES/TRANSITIONS are periods of total confusion and chaos (in my head). I don't know what is happening in his life, but he may frightened of all the expectations/obligations that come with work/marriage/children, etc. Could he be afraid of something that is causing him stress? I was so afraid of what the hell I was going to do after school (even though I was an excellent student) that I left college every time I came close to graduating. I have had the same experience during any transitional phases in my life - even about things I WANT to do.
2. (I'm not sure how long you've had a long-distance relationship for). Perhaps literally and figuratively this has made him feel a distance between you two and that intimacy needs to be reestablished. Perhaps throughout the long-distance part of the relationship he has been spared the "difficult" aspects of relationships - not having to open up as much, being able to be alone more, not having to communicate - maybe he has become comfortable in this situation and fears your desire for "more" from him. He ought to at least be able to give you a better explanation of what is going on - not lame excuses.
3. He may have schizoid traits that would make it even more difficult for him to develop that intimacy. I know schizoids that claim they want to get married, have kids, etc., but often cannot cope with real intimacy. They may prefer something like a long-distance relationship, because it gives them the (albeit limited) social/romantic needs they do have, but allows them to keep their autonomy, privacy, etc. The fact that you have been together for so long makes me think he is not altogether schizoid, but may have a mixture of traits that could account for some of his behavior.
4. I hate to say this and hope that this is not the case, it is just a possibility - but perhaps he cannot commit, has decided or perhaps isn't sure if he wants to continue the relationship and doesn't have the guts to admit it and tell you. Opening up, communicating can be very difficult - especially when it comes to (negative) emotional things. He may be afraid of disappointing you, afraid of anger or resentment on your part, feeling guilty himself - so he is AVOIDING it by not dealing with the issue and being straight with you - and avoiding you, too. The only reason I say this is because I never found the courage to break up with anyone and somehow I found ways around it. I feel terrible about breaking up with anyone and it's just too hard for me to do. Avoidants don't like to disappoint (because this leads to perceived or real rejection).
Is it possible that he is seeing someone else? I hate to even ask this, because I can see you are really in love with him (and he with you), but the extreme behavior does seem odd, especially since you have a long history together and are close to him (probably more so than anyone else in his life).
5. Just not feeling good enough about himself and being a perfectionist. The fact that he says he wants to have enough money to support you, being afraid to send out resumes after law school and so on are signs that he is afraid he is or will be inadequate. I think most avoidants see things in black and white and tend to be perfectionists, they perceive the smallest flaw (in themselves or their work) to mean complete failure of THEMSELVES entirely. He may be very afraid of not being able to live up to your expectations (like in a marriage), but I don't think that should prevent you from expressing yourself - even criticisms. (They just need to be balanced with positive feedback, which it sounds like you probably give anyway). You need to communicate your needs, too, so don't forget to look out for yourself in all of this - it's true in any relationship. You sound like you reassure him of your love plenty, but you could also remind him that he doesn't have to be perfect, that it is okay to have faults and not to be ashamed to show them (especially with you).
My best suggestion is to (in person) confront him in a non-judgemental way. You can gently explain that his behavior hurts and confuses you and that you just want to know what is really going on no matter what it is. If you open yourself up and make YOURSELF vulnerable in a way, he may be able to do so also. See if you can get some real answers FROM HIM by approaching softly and encouraging him to tell you honestly what is happening. Let him know you are prepared to accept whatever it is he has to say. YOU need to know what is happening.
I really hope everything works out for you. If you had a close relationship before I think there is definitely a chance to establish that again, but it means being open with each other (discussing what is happening) - and in this particular instance - in a non-critical way, because he will tell his "little white lies" to avoid saying how he really feels if he thinks you will be critical of it. If you cannot get anything out of him then, well, I think you have done more than your fair share to make the relationship work - and you can't change the way he is. I don't think it means he would be better off with someone who is avoidant. He may just be incapable of some things (i.e. maintaining a stable relationship) because of his AvPD. But you need to live your life too and you can't make the relationship work without his cooperation and commitment.
Sorry for rambling, but I really wish you the best of luck and hope everything works out well for you. No matter what the outcome, remember all of life's experiences are for learning and growing.
Adna