So I'm 26 (f) and have been with my mono (m) fiance since I was 20. Right after I turned 25 I realized I had romantic feelings for my long term best friend (m) of 7 years who is married.
Anyway long story short a little over a year later we all moved in together as a polycule and have been actively working on all our relationships together.
My fiance and meta are both currently mono so we're basically an N formation. My relationship with best-friend-turned-lover only got physical about six months ago and we only started having sex three weeks ago.
And it's absolutely crazy to physically click together as well as we emotionally did when we were platonic.
Both of us had only ever had sex with our "pisces" as we call them (me and him are both Leos so we're like a weird set) so sexually exploring with someone else is kinda weird but also feels amazing and is nothing like initially having sex with my fiance.