My wife's emotions go up and down during pregnancy and I get hurt easily. How can a husband be patient?

Emotional changes during pregnancy largely come from hormones and physical exhaustion, not from any lack of love for you. Understanding the cause makes it easier not to take every word that slips out to heart. The Prophet ﷺ said: “Indeed, gentleness is not found in anything except that it adorns it” (Sahih Muslim, Kitab al-Birr wa as-Silah wa al-Adab). Answer irritability calmly, not with anger in return; give her space when she needs it. Ask what would help, and lighten her daily load. Remember that she is carrying a tiredness you do not feel. Your patience now is a memory of love she will keep for a long time. See communication & emotions.