Swinging and sex with other people is for FUN. Don't make it a serious thing. have the couple over and just have a good time flirting and fucking. go with he flow. Sometimes the women are so into the men that they just love being around the other guy all day, sometimes just for sex.
Have fun, just like you did in high school. That's what swinging is really like, being back in high school but now everyone knows what they are doing.

