I have had a number of threesomes. We had a group of friends that were very open about sexuality. This made it very easy. I had three long term relationships where we had threesomes and a couple of orgies. A few partner swaps for the ones that did not care for groups.
I really enjoyed it. I am average sized but had no hang-ups with the larger males.
One girl absolutely loved sex with other men but was very dedicated to me. She would not do anything without my involvement. We had many sessions with other partners.
She was incredibly good looking. She also had a large penis fetish. The 2 times we had sex with other larger males, she was in pain and complained a bit. She still liked large but would mainly give them head.
Another girl said she was not into that but changed her mind. All it took was a bit of porn and asking her some questions. We had an orgy one day with some friends but she did not swap that day. Things changed after that though. We had many threesomes and she had sex with some of my friends with my consent. She also set me up with some of her friends. She did not like it when I sent her friends into orgasmic states so we had to keep that part separate.
I enjoyed watching her though. There were times that the tag team of 2 men would keep her having orgasms for hours.
The friend of mine with the large penis slept with both of these women. The second handled the size without a problem.
The third one did everything through fantasy. She loved closing her eyes and imagining. She also loved for me to take her step by step through the process. We eventually had sex with another guy. She became romantically involved with him so I moved out. Although she begged me to come back, I couldn't do it.
So, there are dangers to this but lots of fun for those that can handle it.