His ADHD or something else?

My mom said "I'm not sure if this is the 'real' him that you never knew, or if this is a manifestation of the difficult situation he is in. Either way, it does not excuse poor behavior." 

The poor behavior is my bf under-appreciating me, making excuses for not trying to meet my needs, and being condescending to me. I am trying to figure out if this is part of his personality or a defense mechanism for the ADHD thought-process.

He has been unsuccessfully applying to jobs for almost a year. On Monday night I helped him write a great cover letter for a job (I am a good writer and work as an editor) and he barely thanked me. During the week he gets caught up in whatever he is doing and doesn't make time for me. He texts me here and there and doesn't make plans or have real conversation. Last night he didn't text me back for a while (I had texted him wanting to hear about his day), and he said it was because he was "deep in conversation" at a bar with some guy he knew from law school. I told him I don't know the last time we were deep in conversation, and I need him to plan face-to-face time where he expresses interest in talking to me. I tried to explain my feelings, that I am working all the time and feel like he does whatever he wants without regard to what I want. He said he just can't meet my needs, and I said it seems like he doesn't want to because he didn't even try. Then he had the nerve to say to me that he is "really tired of hearing about how I am not working." As if by me saying I am working I am criticizing him for not working? As if I would criticize him after helping him with the letter? I told him I don't feel appreciated in regard to helping him with the letter, and he just said "I really do appreciate it, but I'm still applying, still moving." It sounds like he is a celebrity looking for his next role! 

He is not showing appreciation or humility. He only calls me or sees me when it is convenient for him. He gives acquaintances more undivided attention. He isn't close enough to anyone else to where they would actually tell him their feelings and expect him to consider them. He constantly tells me I make him feel not good enough, and then he acts like he is better than me and doesn't have to address my feelings. He has been acting more this way since he has been living with his parents and siblings, who have a superiority complex and are rude to each other. My mom said he is treating me like the enemy, which I have said before. He is lovey-dovey on the weekends when we are together and then treats me this way during the week when he is living at home. Can someone try to help me understand if this is ADHD or something else?