Make a prediction about the change in Patrick's behavior. How might his change affect Mary?

I have a feeling that the reader is supposed to answer this question before he or she has read the entire story. I think the question is asking the reader to analyze Patrick's behavior after he first gets home.  

The reader has never met Patrick before, so it's tough to get an initial read on him when he first walks in the door. He is not very talkative, and when he does talk, his...

I have a feeling that the reader is supposed to answer this question before he or she has read the entire story. I think the question is asking the reader to analyze Patrick's behavior after he first gets home.  

The reader has never met Patrick before, so it's tough to get an initial read on him when he first walks in the door. He is not very talkative, and when he does talk, his responses to Mary and short and sweet. There is no way to know if that is odd, though. The first hint that the reader gets about Patrick's change in behavior comes when Mary mentally states that Patrick did something odd.  

"Yes," he sighed. "I'm thoroughly exhausted. And as he spoke, he did an unusual thing. He lifted his glass and drank it down in one swallow although there was still half of it left. He got up and went slowly to get himself another drink.

That right there tells the reader that Patrick normally will only have one drink. Why is he having a second? Also, why did he quickly drink the first instead of savor it? It seems to me that either Patrick had a rough day and wants the alcohol to help him forget it, or, he is quickly trying to get some liquid courage into him. The reader also learns that his second drink is a very strong one.  

For the next few paragraphs, Mary attempts to stand up and get something for Patrick, but he keeps telling her to sit back down. He doesn't want anything from her. Uh-oh. I believe that this moment is when your question is meant to be answered. Patrick's behavior is odd. The text is clear that his behavior is not normal. I've known my wife for 18 years, and I know how I react when she is acting "not normal." I get worried. Inherent in worry is a bit of fear. I believe that Mary is beginning to become worried that something is wrong with Patrick, her, their marriage, or his job.

It turns out that Mary is becoming frightened.  

She stood up and placed her sewing on the table by the lamp. "Sit down," he said. "Just for a minute, sit down." It wasn't until then that she began to get frightened.