I really need advice on how I can convince him that other guys aren't a competition and that I'm not trying to replace him. He does tend to over think, over react, and over analyze.
Not really your job to convince him.
The choices as I see them are these:
1) You keep living together. You stick to the agreements you made about other dating partners being over.
2) You keep living together. You tell him you tried it on and the agreements do not work for you and you cannot keep them. You would like to renegotiate new ones you CAN keep rather than cheat on agreements.
3) You stop living with him so these agreements about partners in shared space don't even apply. It's all your home and your space.
4) You stop dating him entirely.
All those things you can speak up about, decide, or do on your own.
If is he IS willing to to something to work on his jealousy... then you get a few more options.
Maybe you could read through these and talk it out. Get the
jealousy workbook. And/or see a poly friendly counselor.
http://www.practicalpolyamory.com/images/Jealousy_Updated_10-6-10.pdf
http://www.kathylabriola.com/articl...nster-managing-jealousy-in-open-relationships
http://www.kathylabriola.com/articles/jealousy-first-aid
http://www.kathylabriola.com/articles/are-you-in-poly-hell
But if the bottom line is that he wants a One Penis Policy and you do not want that? It's your job to say a clear "No. I do not agree to that" and let him figure out if he wants to work through his upset or not. You cannot do it FOR him.
You can help, but if he prefers to hang on to his upset? Then he prefers to hang on to it. Then you have to decide if you enjoy dating him that way or not.
If he only agreed to being in an Open relationship with you to gain access to you and be in your orbit? Then he really wasn't choosing to be in Open relationships because HE enjoys being in them. He's only doing it to get access to you. Or thinking that him doing something he really doesn't want to do is somehow "proving" his love for you.
If that's what is going on, I think the kindest thing you as a hinge can do is cut him loose so his upset has clear end point. Don't let it be never ending suffering.
He can stop being upset about the other dating partners, and be upset about a break up for a while. Then heal and stop being upset about the break up. His suffering ends rather than being never ending upset because you ARE going to date other people. Maybe he learns not to get himself into situations that are not right for him just to get to date someone.
Galagirl