Personally I would ask for a little bit more from a relationship. If I had somebody continuously snapping at me I would think that it was someone who lacked respect for me, who lacked self-control and who had a bad attitude. All indicators of future behaviour that would only make me miserable.
That's not how a mature adult communicates. It's how an angry little child or a disgruntled dog expresses themselves. I wouldn't be going off buying books and trying to figure this person out...I would walk, before I got too far sucked in and too emotionally attached. Life's too short.
...However, that said, I would wonder why you feel the need to tell him that you are feeling down? Is he your counselor or your boyfriend? Are you leaning on each other in recovery? Are you leaning on him? Are you looking to enhance each other's lives or drag each other down? If he asked you when you are feeling down "and is there anything I can do for you?" would there be anything he could do? Probably not, but you could exercise several options...go for a walk for one. Then eat a banana. Listen to Dj Tiesto's "Traffic" (extended version). Do something for someone else.
It's like people that go around telling others that they are tired. What do they think that is going to achieve. It's an exercise in futility. It's complaining instead of doing something about it.
Sometimes you need to work on your own self esteem and confidence before you can contribute to a healthy, loving and secure relationship. But some people choose second best and an unhappy life instead.