This itself is a symptom of a far worse problem. It's not bad enough that Elly has no idea who the people Mike associates with are and no inclination to care; what's really horrible is that she has no idea who Michael himself is. In her haste to make her life perfect, it would seem that she neglected to learn who the little boy who clearly hates her actually is and whether he actually does spend his time wondering how he can torment the mother he clearly seems to want to destroy. She never seems to have picked up on the fact that he lives with the fear that no one really likes him because she just can't bring herself to find out who he is, what he wants and what he likes lest she suffer the humiliation of knowing that she worried about nothing.
The same unreasoning fear of being seen as weak is why she never seems to take the time to explain who she herself is or what she wants. Never do we see her share her interests with her children so that they may know that she isn't the fun-eating, child-hating monster who only had kids so she could have someone around to boss around and to hate that they see her as being. This, of course, is owing to their knowledge of the one thing that she has actually shared: her belief that having to be a mother to small children is a humiliating waste of her time. They do know that she thinks that if she hangs around them too long, her brains and self-respect will go bye-bye and she'll be as worthless and useless as she tells them they are. Simply put, she doesn't want them to know what she likes because they're sure to get their muddy, grubby little hands on it and ruin it forever.
This leaves us with the baffling question of why John would think that this idiot is what he needs raising his children; she clearly detests their company and clearly seems to think that being a mother would be a snap if she didn't have to deal with kids.