Originally Posted by SchrodingersCat
The two things that jump out at me are:
a) that he said he would drop her tomorrow if you would go mono with him
b) that you don't like him having another girlfriend, even though you have another boyfriend
Regarding (a) that's a red flag to me. Even though this is your thread and it should be about you, I have to say that's kind of a jerky thing to do to this girl. She's probably expecting a relationship, but he's just using her to keep distracted when you're out. It would be more appropriate for him to find some other friends or a hobby to keep busy with when you're out, rather than taking advantage of that girl.
Actually that very same thing happened a couple of months ago. I thought that since I was seeing someone that he HAD to see someone as well so I pretty much forced him to start talking to someone. And well, he wasn't so honest about our relationship with her knowing it might scare her off and it ended up a HUGE f'ing mess to the point where I can't even visit him at his work when she is there. So he didn't want to make the same mistake and has been honest with this new girl as much as he can be. But when i first met her he actually asked me to not get into everything with her so I wouldn't scare away someone he really thinks he could like. I said I wouldn't bring it up but if she asks me, which she did, I was brutally honest. Which is why she IS weirded out a little right now and said let's just have you show me the dj'ing and be friends and see where it goes giving her time to adjust to our alternative way of life.
(b) is basically your issue and you need to overcome it. Fine, your boyfriend thought he was mono and so you figured you would never have to deal with jealousy etc. Well, surprise! He's not feeling so mono anymore, and you have to go through the same shit you're asking him to go through. That is assuming, of course, that he truly feels poly and isn't just using her, see (a).
Yes it is...and I am working on it. I hold back my tongue and emotions when she comes up, but I did tell him that I just got used to the idea that we could have a poly/mono relationship and now all of a sudden he's talking to someone else and I know he wouldn't be if I wasn't in the first place. I've tried to tell him there's other things to occupy his time but he's never been someone who has close friends. His best friend IS his partner, so without me, he feels left alone and abandonned. He DOES want to be with me 24/7 so when he's not and on top of it i'm with another man, the only way I guess he can cope is having someone else that he can speak to on an intimate level. He said work with him on this, b/c this will only help him understand how I can be with my secondary but still want to be with him. He IS giving me a taste of my own medicine which is why i can't say too much. He was like when i talk with her, you're right...i'm in my world with her instead of obsessing over me and my secondary and letting his anger build and build. So maybe it IS a good thing?