My two men are mono, but aren't able to answer you directly. Language boundaries and such. I will translate the discussion that ensued when I asked them your question
Lin: Poly wasn't the matter for me. Phy could have been promiscuous, or could have called it whatever you can think of, it was the same for me. In the beginning, when we discussed the topic (I was still at home, separated from them), I wasn't envious that she could love more than one, I was envious that Sward was able to get what I wanted to have. When we processed to a more practical handling and I got to know Sward better, we met and talked, the envy vanished in that regard and a new issue arose: They knew each other so much longer and every time they talked about 'Ah, do you remember this or that, wasn't it fun?' envy hit home again.
Regarding the sex-matter: Yes, of course it isn't a pleasant feeling at first, but it depends tremendously on the other partner. On which level of friendship you are with him. Do you hate him? Do you envy him? Do you accept him/ still feeling uncomfortable? At that stage it depends on what type of guy you are. If you are like
(Sward skipping in) having no problems with your wife being intimate with another man, in a certain way even like to think about that.
(Lin again): Yeah, right, you are strange *pokes him* Or one proceeds as I did: You accept that there is another one, doing different things with your spouse that she likes, having been together long enough to know everything about her and such; But I am mostly pretending to just have a mono relationship with her. I don't think about Sward, I am satisfied with what I have with her and I normally don't think about her husband at all. It's just OK. I can't say that I still have problems with them being intimate most of the time.
But the most important point for me is: How does my partner behave? The poly person of the relationship just has to get across that she is able to distinguish between the other persons who are in a relationship with her. Phy did that right from the start, tried to explain to us that we are so different, giving her different things, evoking different feelings and such. This assurance isn't necessary all the time, but it has to come across as true and secure, because the real understanding how 'this poly mind' works will never be there for a mono person. It helped me when she pointed out in what parts her husband and I were different, taking note of special personal traits and quirks, expressing that she liked this particularities about me and so on.
You don't have to see the other person as a friend in all cases, but you have to be able to accept him in her life. Comprehending that she loves another person like she loves you *jokingly* like she preaches: one level for all, no one is more important to me, no hierarchy, one level for all .... *serious again* and the most important point: She has to get across that you are something special, giving her something that the other isn't able to give her. That's how it works for me. And talk! Communicate, communicate communicate. Lot's of communication helps. *smiles*
Me to Sward: Anything to add? Initial thoughts?
Sward: Well, my situation has been different. I have been the one who has been in a long relationship with her, I had to share suddenly. It took a lot of trust in regard to her. I had to trust her that the love was strong enough that she wouldn't leave me, that this wasn't a scam, that this was truly what she felt. At first, I lost some of that trust, because it was so new. But when I talked to Lin, I regained that trust, when we build this friendship, it helped to deal with this situation because we got along with each other.
I liked talking about Phy with him, exchanging experiences and ...
(Lin skipping in)Yep, profiting from experience of the person who has been in the relationship longer, knowing all her spleens and quirks *laughs*
Sward: Yeah, right *grins back at him* But talking about problems as well.
In regard to physical intimacy: I am a bit different, I like thinking about stuff that they may do with each other, therefore I don't have that many problems with that side of things. Emotional intimacy was my problem when things got started. What would have problematic for me, would have been to maintain different households. It is important for me to be able to see them, experience them together, share chores, helping each other …
(Lin skipping in) But it would have been problematic if we would have been more like alpha males. This works because we are both like we are, *glancing at me* we have our alpha right there ….
Sward: Well, I even clean your room from time to time when I got the mopping water ready and am at it.
Lin: Right, that's what I mean, we are homemakers.
Sward: And finally: Communication is the key
Aren't I good at taking minutes?
Well, maybe this helps to satisfy your curiosity.