Former swinger here chipping in way late on the conversation. While I had my fun I really only did it because I was foolishly in love with the wrong person. It was her idea. One night when we had just started dating, we went to visit friends of hers and we had all gotten very drunk. Then my ex started hanging all over her best friends boyfriend. Naturally I became very angry but then I noticed her best friend looking at me like a lion staring down an impala (I also think it's worth stating that I had fantasized about fucking the best friend the whole night). I was so naive at the time that I thought she was mad at me for allowing my ex to act that way. So I stormed out out of the house and walked down to the beach to cool down. The next thing I know the best friend finds me and begins making out with me not even allowing me to speak, and we had amazing, sandy sex on the beach. I was really quite shocked by it all and went home alone afterwards to reflect. The next morning I woke up and did my typical bring my ex her favorite fast food breakfast and we had sex and afterwards she basically talked me into having an open relationship, saying that in her home country of South Africa, it's normal, and people don't become monogamous until marriage. So we remained that way for over 3 years. And every time it killed me inside but I kept on with it despite the fact. Now I'm a typical redditor, in a long-term relationship with my right hand and xvideos and haven't had sex in months. If your wondering why, despite my responsible use of condoms during that phase of my life, she wasn't so responsible, and gave me herpes. It's a real game changer.

Tldr? Swinging sucks, it never works in the end, and it often leads to STDs.