Discuss boundaries with your girlfriend. Co-ed slumber parties with her ex-boyfriend are a no-go, as is greeting a non-related male with a kiss on the lips. Convey what makes you uncomfortable, but be reasonable. If you can’t take her hugging her hot first cousin, you have bigger issues to deal with.
Confront your fears. Your imagination just may be running away from you. Go out with your girlfriend and her friends. See how innocently the other half really lives. Meet her guy friends. See how much chemistry they don’t have and how much of a stud you are in comparison to them.
Inquire if you are in doubt. If you are uncertain about the nature of the relationship your girlfriend has with an individual, casually and innocently ask. Getting a direct and honest answer could squelch your jealous fears. Be careful not to interrogate or cross-examine.
Pinpoint your trigger. Determining what triggers your jealousy may help you address these feelings. Is it a specific individual, the way she dresses or something deeper? Is your girlfriend ignoring the fact that her hot, successful best friend is in love with her, or are you so insecure that your imagination has her cheating with every breathing male within walking distance?
Control your stress levels. Soothe your anxieties with activities such as meditation or exercise, suggests psychologist Craig Malkin in the Psychology Today article, "Five Ways to Kick the Jealousy Habit." This will make you less likely to lose your temper or say things you don't mean. When you need a quick solution for your rising jealousy, take a moment to practice breathing exercises until you regain control over your thoughts.
Seek therapy. Jealousy stems from person insecurity -- usually fear of loss or abandonment. Depending on the severity, you may want to consider getting professional attention. Your jealous behavior may be a symptom of a bigger affliction.