To be honest, we are not told much about the character of Patrick. Far more is revealed to us about the character of Mary Maloney, his wife. However, we do know that he is a senior, high-ranking policeman and that he works very hard at his job, as he comes back tired from work. Although we are not told specifically why he is leaving Patrick, we can perhaps infer he has a mistress that he wants to live with and leave Mary. This shows he is leading a double life and has been for quite some time. Above all, we can say that he is a selfish and self-obsessed man. Note what he says to Mary:
"And I know it's kind of a bad time to be telling you, but there simply wasn't any other way. Of course I'll give you money and see you're looked after. But there needn't be any fuss. I hope not anyway. It wouldn't be very good for my job."
Note how he is more concerned about his job than he is concerned for Mary and her feelings at hearing this terrible news. Thus, although we are not told much about his character, we can infer that he is a selfish man who has been practising deception for some time and is leaving his wife at a terrible time during her pregnancy.