Both sexes

Has anyone had boyfriend and girlfriend at the same time? Whether secretly or all three knowing about each other?

Yes very good friends of mine lady asked if I would let her boyfriend strip me and play with me while she watched I really enjoyed the experience and were sucking each other while she watched us using her vibrator. She joined us and tried inserting it in my butt. It didn't work out then but it did on other occasions. It was awesome

My very first bi experience when I was very, very young happened with a friend from school. We BOTH had girlfriends which made both of us extremely tired most of the time. The girlfriends didn't know a thing about it.

I was the other guy to a married couple I knew. I would go to their house and we’d play. I would fuck his wife and suck his cock at the same time. When I was there he wouldn’t fuck his wife till I had cum inside her. As soon as I pulled my cock from her wet and sloppy pussy he’d shove his cock in and fuck her till he also filled her with his load. Was truly a fun time!