Richard Ford's Wildlife is a coming-of-age story in which Joe, the teenage protagonist, moves to Montana with his family so that his father can find work. This ends up being a firefighting job, which keeps his father away from home, and in the meantime his mother begins an affair. Joe is aware of this and his insistence on not blinding himself to reality forms the cornerstone of his maturation in the story.
Joe gives his mother a brief introduction at the beginning of the story, opining that she thought Montana was too cold and lonely, but that otherwise she probably thought their life was a normal one. His representation of her at this point does not insinuate the complexities that develop later in the story.
Joe and his mother have ample time to spend together, in the wake of his father's absence, although Joe tends to be quieter and more introspective than his mother, who seems to have been personally changed or challenged. Much of the dialogue can be seen as foreshadowing, particularly in the presence of Warren Miller - for example, Joe's mother states that "everyone does everything eventually", and Miller gives Joe a knife and advises him to choose his battles carefully. Fire, particularly the wildfire that Joe's father is fighting, is frequently used as a symbol of dangerous and uncontrollable things.
Joe tends to act somewhat one-dimensionally from the perspective of other characters in the story; they talk to him, not with him, and usually get short responses that suit their expectations and do not give insights into the observations that Joe is actually making in his narration. Joe's mother seems to drink frequently, and reflects on disliking her name, and the way that children perceive their parents. Ultimately much of this comes across to the reader as an identity crisis and justification for her infidelity, but to Joe it mostly seems strange and confusing; at this point he doesn't truly understand why she is acting this way, or involving him so closely in it (i.e. making it very easy for Joe to discover what she's doing with Miller).
There's a degree of interpretation possible in this relationship, but in the end I think it approaches a sort of lopsided dependency; Joe is impartial, naive and quiet, and his mother is slowly falling apart. He has a firsthand account of her transforming from his father's wife to Miller's mistress, and he can see her and his thoughts about her shifting between these two identities. She seems to spend more time as a woman, albeit one who acts strangely, than she does as a mother. Their relationship is certainly not a typical mother/son one; my impression is that Joe simply has no idea what to do, but he does have a sense of how things should be. His mother is looking for someone to, basically, tell her "yes" or "no", and Joe, who should be telling her "no", is not mature or aggressive enough to understand or assert this role. At the end of the story, as Joe reviews some of the letters she has sent him, it seems clear that she has exited the role of mother and is no longer a real part of Joe's life.