Quoting 35 Weeks, 👣:" Its Not That Im Okay With It, Because Those Plus Other Reasons That Aren't Listed Are Reasons Ive Packed ... [snip!] ... Sites. >.< Cause He Has A Complete Different View When He Sees Me Packing My Belongings Up & Telling Him Im Leaving."
Give him an ultimatum. Tell him he needs to stop with the hook-up sites or you are leaving, end of story. It may take you leaving, even if only for a few days, for him to get the point. He might want to get some counseling if it's impulsive