Football-wise, The good thing is that we have plenty of forward options and don't have any actual important games coming up. This means Southgate can do what he should have done with Maguire and tell them they won't be considered for the next 5 - 10 games.
Next breach of discipline costs...
As for Foden's Mrs, at home looking after his kid ... in my experience, women tend to be quite understanding about this sort of thing. On his return, she'll probably just ruffle his hair, call him a "cheeky one" and they'll all be laughing about it by xmas
I think it's to do with setting the culture where everyone knows how they will be treated if they transgress. Picking Maguire sent a clear signal to go push some boundaries.