My first serious boyfriend was a really perverted, creative guy in the sack. He loved experimenting with different toys and putting me in different positions and stuff. But one limitation I had always had was anal. It wasn't that I was against it in principle, but every time he would initiate it, it just didn't feel right so I would stop him. To his credit he was never pushy – I think he was confident that he'd get his dick inside my asshole sooner or later so there was no rush, lol and boy oh boy was he right!
When he first proposed a threesome I was completely taken aback, I thought he was the super protective and jealous type of bf. But when he described his fantasy of seeing me filled from both ends it sounded really hot and got me wet and eager to please him, so I agreed. He invited a buddy for the threesome who happily filled up my mouth with a thick cock while my bf started getting creative with my pussy. It wasn't long before I was a wet little heap stifling my moans between their two cocks and basically a slave to whatever they wanted to do to me. And that's when my bf did it - confidently stuck his finger up my ass and for the first time instead of clenching up I just moaned and let all the tension release. It was the most erotic sensation in the world and it wasn't long before his dick was inside my asshole filling me up as he was fingering my wet little pussy to climax. I couldn't even moan properly because of the second dick in my mouth which somehow made it 100x hotter than normal sex.
Eventually I lost control and came (several times). It was the most unexpected pleasure I've ever experienced and I have yet to experience anything like it again.