This movie is a character study, meaning the plot is not the main attraction, nor was it meant to be. The plot is used mostly (almost fully here) as a vehicle to showcase the character-- and that it does, and beautifully so! I was never a HUGE Julianne Moore, and now, after this movie, I see her artistry; and the range and depth of her skill fully.
John Turtorro, on the other hand, is my favourite male actor, or at least at the top of them of my list. And he never disappoints. The reason he was cast here is not for his looks or his chemistry with Julianne Moore (although I would argue, it's there, in its own subtlety and form). He was cast for his sincerity combined with his quirky.
His character behaves badly, this is true, but Turtorro's portrayal lets us know, almost wordlessly, that the feelings he has for Gloria, including the delicate beauty he sees in her, couldn't be truer, for all his cowardice. The acting informs us that his failings are his own just as Gloria's silliness, resilience, and overall luminosity are ALL her own. I hope Moore, Turtorro, and writer/director, Sebastian Lelio are all dominated for awards on this movie; exquisite work.