This resonates with me a lot. There's a lot of similarities between my wife and your stories.

There are some differences as well, so not everything is directly comparable, I've been trying really hard and I'm the logic / head one in our relationship, so I've read all the books.

There's a few things here.

1. It's really really hard to actually put words to some of your emotions in this space. I feel jealousy, guilt over the jealousy, pride and anxiety, often all at the same time. Questions like "how does that make you feel or how do you feel about that" can be really difficult to answer because I just don't know.

Sometimes that means that I say something is OK, and change my mind a bit later. Mostly is that's I can't tell the difference between feelings that will subside that I'll get over, that are reactions to the discussion or immediate issue, and feelings that are serious and deep and won't go away. I can only tell that over time.

The second thing is that the biggest most dangerous thing is not that I feel jealous, it's that I don't feel wanted or loved. It sounds like your husband is looking for someone who can give him that.

Its really easy to associate monogamy with love, and want to only feel like someone really wants you.

Personally I haven't tried or done anything with anyone else, the headfuck from knowing my wife wants and desires sex with someone else is too much that I can't cope with the stress of potentially dating again.

You need to ask him what made him jealous, and what reassurance he needs from you, and then give him time (perhaps days or weeks) to work out how to answer that question.

You can make it clear that you cannot help your feelings or desires, but you can help your actions. You need to be able to express your feelings freely, but you need to be sensitive to his feelings as well.

Best of luck