I've been in the "lifestyle" for over 12 years now.
I live with a (socialite) swingers couple that's in a "private" group. (see my profile)
On average I'd say 20 parties per year at different locations, always at the homes of member couples.
Similar to what "luckyseven" wrote, swinging is a healthy outlet and means to strengthen relationships and as a social and recreational interaction with others.
And you need to realise that swinging is about sexual experience(s) not love.
Due to the fact that this couple is very well connected in media in general and music in particular, I've had, let's say, "interesting encounters" with two women that could both be called world famous.
Any other questions send me a PM.