Peter
How do you know? Have you talked to him about it? Honestly? And no, you shouldn't have to do monogamy if its not your thing. But you should let him tell you no instead of assuming. Because you're not happy, and its not just Jerry, its not just the Seal, part of its this.
Just think about it, all I ask. Think about if its worth it to be that open with him, weigh up possible gains against possible losses.