Observe your friend when he interacts with others to determine whether his snappiness is directed at everyone or just you. If he is short with everyone, it could mean he is going through a rough patch with his family, school or work. If it is only with you, there might be something you said or did that offended him.

Tell your friend that you've noticed him snapping at you. If he seems surprised, it is possible he was unaware of his behavior. Don't be confrontational. It is best to make "I" statements such as, "I feel hurt when you snap at me," rather than "you" statements that sound like an attack, such as,"You've been snapping at me." Remember your goal is to get him to recognize his behavior and correct it, not make him defensive.

Rule out physical conditions that could be creating the problem. Ask if he has had trouble sleeping. Perhaps he's had an increase in workload and hasn't been able to get enough rest. Migraine headaches can also cause irritability. Perhaps he just quit smoking or is on a diet that he finds frustrating. Encourage him to make a doctor's appointment to rule out health issues.

Communicate openly and honestly with him. Let him know you have noticed his irritability and want to know what is bothering him so you can help. Ask him if you've offended him. He might deny there is a problem. Express concern for him, but don't be too persistent or start nagging -- that's likely to make him more hostile.

Tell him how much you care about him. If you discover that he is going through a stressful period of life, be supportive. For example, he might be experiencing difficulties with a new boss. Listen to his complaints and offer sympathy. Help him see the optimistic side to his situation, if there is one.

Determine whether he has developed romantic feelings for you. If you recently started dating someone new, his jealousy could cause frustration. He probably won't want to declare his new interest in you if he believes his feelings aren't reciprocated, so you might need to rely on subtle cues to verify your suspicion. If he does have a crush on you, it is probably best to give him some space for a while. On the other hand, if you are interested in taking the relationship to a new level, confessing your feelings can bring you both unexpected happiness.

Consider the possibility that your friend might be experiencing a problem in his relationship with his significant other. Jed Diamond, a noted author who holds a doctorate in international health, explains in his Huffington Post article, "Jekyll and Hyde, Irritable Males and Attachment Love," that men often become snappy when they feel insecure emotionally. If your friend is having difficulties in his love life, it is not uncommon to lash out at those around him to cover up his sense of vulnerability. Show your friend additional affection when he needs it.