Complex sentence: John enters a depression that only worsens when Max and Ariel begin spending time together, culminating on Christmas Eve when his daughter Melanie comes over with her estranged husband Mike (Christopher McDonald), whom John is not fond of.
Split into simpler sentences: John enters a depression that only worsens when Max and Ariel begin spending time together. To make matters worse, on Christmas Eve, his daughter Melanie comes over with her estranged husband Mike (Christopher McDonald), whom John is not fond of.