I'm Liama, and I'm part of a polyfidelitous quad that's been struggling along for about 2 years now. All four of us are in our early 30's.
I've been married to Felix for 10 years. We are new to polyamory, yet throughout our relationship we have occasionally opened up for specific individuals. The biggest step came 6 years ago as we began having sexual encounters with my childhood best friend, which occurred perhaps monthly for about 2 years, though she insisted the sex was separate from the friendship in her mind. I viewed the situation as friends with benefits more than an established triad, though the boundaries were murky...for me anyway. The experience revealed to me that I'd like full love relationships with outside partners, not only sex.
Michael and Dana have been married and fully monogamous (prior to us) for 6 years. They have two young sons, ages 3 and 5. We are good friends who got a little carried away one night over drinks. ;-) We had a good time, we decided to keep dating, and within a few months, everyone was in love. Dana and I are bi and have a sexual relationship, but Felix and Michael are good straight friends and love the term "bromance" to label their relationship.
Overall, Felix and I have found this an easy transition due to having some experience, Michael and Dana have struggled with jealousy much more. Michael's jealousy was intense in the early months, then something clicked for him and he's rarely bothered by it anymore. Dana has had the opposite reaction: she never seemed to feel it until we reached year two, and we are now in a situation where 3 of us want a group marriage, but Dana wants to keep all partners outside the original marriages as secondary, with lots of space between and veto power as an option for primaries as needed for things like sex and time spent together. This has been a source of grief for all of us, but we're limping along trying to figure it all out.
Nice to find this forum, and hopefully I'll make some good friends here!