There are many books on the subject of jealousy around the call number BF575.J4, such as Romantic Jealousy: Causes, Symptoms, Cures. Jealousy is an apprehensive, fearful emotional state that comes from a lack of trust. If you find you’re often jealous, you need to work on trust. The counseling office (bit.ly/BC-counseling) can help. If this is a specific situation with a specific person, have they done something to abuse your trust? If so, it’s unlikely you can overcome that without some effort from them. If not, then work on trust.