Men tend to have more sexual than romantic jealousy. Whereas women tend to feel more romantic jealousy. So studies consistently show that men experience more sexual jealousy and women experience more romantic jealousy.
When college students are asked "Would you rather have your mate fall in love with someone else or have sex with someone else?" Men usually say "I would rather my partner fall in love with someone but not have sex with that person." Whereas women would generally say "I would rather my partner have sex with that person but not experience any kind of love toward him or her."
Jealousy's not always a bad thing. Jealousy as any feeling has a protective component. It alerts us that something is wrong in the relationship. That perhaps we're taking our partner for granted or perhaps something needs to be changed about the relationship. In that way, when the jealousy is reactive, when you're reacting to the way your partner behaves, it's a healthy and normal emotion. It alerts you that something needs to be done. Perhaps the issue needs to be discussed and some things need to be changed in the relationship.