I would have to say that I feel sympathetic towards both Patrick Maloney and Mary Maloney. Patrick's decision to leave his wife is undoubtedly brutal, but he seems to realize that he is hurting her very badly and feels guilty and ashamed. That is why he has to fortify himself with so much whiskey.
When he came back, she noticed that the new drink was dark amber with the quantity of whiskey in it.
To make a highball that was "dark amber," Patrick would have had to use four or five ounces of whiskey. Bourbon itself is dark amber. (Perhaps this would explain why he was such an easy victim when Mary hit him with the frozen leg of lamb?) I can identify with Patrick. He is tired of being mothered and smothered by his loving, attentive wife. This bit of dialogue is significant:
"Yes," he said. "I'm tired,"
He is thinking that he is tired of her and tired of marriage, tired of having to answer so many questions when he gets home, tired of having her watching him and fussing over him.
I am reminded of John Collier's story "The Chaser" in which the man who sells love potions warns his young client that there is a downside to love and marriage.
"How carefully she will look after you! She will never allow you to be tired, to sit in a draught, to neglect your food. If you are an hour late, she will be terrified. She will think you are killed, or that some siren has caught you."
In Shakespeare's Hamlet, Claudius tells Laertes a profound truth when he says:
There lives within the very flame of love
A kind of wick or snuff that will abate it. (4.7)
Patrick has fallen out of love with his wife. He sees that if he remains married to her he could be stuck in this claustrophobic domesticity for thirty or forty years. Young people who get married usually do not see that it is such a long-term commitment. One of Tolstoy's characters says that he and his wife were like two convicts who hated each other but were manacled together by the same chain.
Mary Maloney still loves her husband. Perhaps she would love him for the rest of her life if he didn't leave her. She would even have more babies and make the knot even harder to untie. It is easy to sympathize with Mary, especially since she is six months pregnant and, further, since this blow is entirely unexpected. I can feel how hurt she must be by what Patrick says to her while he is downing his king-size highball.
And he told her. It didn't take long, four or five minutes at most, and she say very still through it all, watching him with a kind of dazed horror as he went further and further away from her with each word.
Love can turn to hate and often does. In Mary's case her love turns to hate very quickly, but her spontaneous reaction seems credible. After she has killed her husband, I sympathize with her in her desire to get away with the murder. I don't feel especially sorry for Patrick. He is a secondary character. It is really Mary Maloney's story. It is told entirely from her point of view. I am amused and delighted when I see how she destroys the evidence by cooking it and feeding it to all the cops who are searching high and low for the weapon.