I'm new at this poly thing. In fact, I'm not even entirely comfortable with identifying myself as such. I'm just a woman who loves two individual men, not necessarily someone who inherently feels the need for multiple partners.
I have a husband (DH) of 15+ years, and now I also have a significant other (SO). I love them both more than words can say. I consider them each to be a "best friend" and a "lover"...although SO and I are taking our time about sexual stuff, so that hasn't gone far yet.
I had never thought about bringing anyone else into our monogamous marriage, but then SO came into my life. Cheating on my husband was never an acceptable option, but neither was keeping SO at the level of "friend who I can't really love as deeply as I feel, because I'm a married woman". So I took a risk and told DH how I was feeling, and explained that I hoped we could bring SO into our lives. I explained that I still love DH as much as ever, and my love for SO is not because of anything that DH lacks.
DH did a lot of soul-searching and ultimately decided that this was something that he would support, because he loves me, and because I was completely honest and upfront. And also because he can see how SO enriches my life, and is not a threat.
So that's our basic story. DH and I are in our mid 40's and SO is in his mid 50's, so I like to think we're being pretty mature about it.
The one thing I'm starting to wonder, though, is how to handle social situations with other people. SO and I belong to an activity-based social group, which DH does not attend. The other members can see that SO and I are close. We arrive and leave together, talk about places we've gone together, and tend to stand close, like a couple. And when I look at SO, I probably have a dreamy look on my face! lol They also know I'm married, because I have a ring, and I sometimes mention my husband, but they never see him. (He stays home with the kids on those days. He's not particularly interested in the activity we do.)
I don't want people thinking that I'm fooling around on my husband, but I also enjoy being free to be openly affectionate with SO. (Not blatant snogging, but being more affectionate that I would ordinarily be with a man, being a married woman.)
I suppose we should just act as comes naturally, and deal with questions as they come. Any tips or experiences anyone wants to share would be welcome, though.