Thinking of somebody else

My BF and I have a good sex life, but like every couple that has been together a long time it has settled into a routine where we know each others bodies, what works and what excites the other. There have been few surprises recently until one night last week. We were in bed, touching each other, me stroking his hard cock slow while he fingered my clit and sucked my tits. As ever it was hot but it is always hotter when we talk so I started to ask him what he had fantasised about recently. He said he likes to jerk off thinking about me with another man, and I started to tell him some hot stories from my past, fucks I had really enjoyed, which increased his throbbing and thrusting in my hand. He asked if I ever thought about fucking another guy now. Answering honestly, I said I sometimes have "memory wanks" about old lovers, especially hot one night stands and that I sometimes get off thinking about fucking a stranger, either male or female. So he then asked me to think about men I know in my life who I would fuck. I thought of one or two. A younger guy at work and a guy who I've seen playing tennis and football at the gym but don't really know. He said he didn't want to know who but he wanted me to close my eyes and picture someone I would really like to fuck just once. I closed my eyes and oddly the face that came into my mind was a third guy, another guy who trains people sometimes at my work. He's quite funny and confident and I've always thought he was sexy without ever actually thinking about fucking him! My BF asked if I had someone in mind and I said yes. He said to imagine that the hand between my legs was this guy's and that it was this guy's cock in my hand. I can't tell you what a huge and unexpected turn on it gave me. I squeezed and tugged at his cock and his fingers were sliding all over my cunt as I felt myself getting wetter. I was vividly imagine the guy moaning, getting erect because of me and sucking my tits while he fingered me. My BF could tell how much I liked it and after a few minutes of lovely rubbing, he slid down my body and started to lick my stiff, throbby clit. Now that he wasn't visible at all I opened my eyes and imagined the trainer guy licking me. My BF was licking in little hot circles, trailing his tongue around my clit and then sliding his fingers up my cunt. I was soaking and moaning and thrusting against (in my dreams) the guy's face. Just as I was about to come, he stopped and quickly restarted, I came hard, pushing my cunt into his face as he licked me. Then he told me to turn over. This was great as I was facing away again and I felt the guy from work's big hard cock slide up inside me from behind. Felt sooooo good! Then he started moaning and saying "I've been dying to fuck you for ages, Andrea, I masturbate thinking of your body at home, I think of you when I fuck other people!" FUCK that turned me on and I started to come immediately. He kept on pounding away and as he did the other two guys I had thought of came into my head as well, like I was being fucked by one after the other. The sexy trainer, the young guy with his cute smile who is a bit nervous with me, the guy at the gym. I was in my own private orgy with three men who I wish i could fuck. And a fourth man getting all hot and excited at the idea. I wouldn't act on this IRL but what a hot, hot fantasy. In the past I have sometimes thought of other men and women while having sex, but never with my partner's encouragement and never did I think it would turn him on so much. When he came, he really thrusted like mad and moaned loudly, his cock pulsing between my legs as I dripped all over him it seemed to go on forever and I came twice more, one of them with the young guy, one with the trainer! The young guy is maybe 12 years younger than me and the taboo nature of it was a turn on. My man did ask me later who I thought of and I said nobody important, he left it there which I think is good, you need a bit of freedom to fantasise! Anyone else done this? I can highly highly recommend it!