Who, What and When are We?

Bob Farmer has hit the jackpot. In a flash, he got a highly-paid position with a prestigious research company and found a new, beautiful and incredibly sensual girlfriend, Zara. Bob’s life suddenly seemed too good to be true. As it turns out – it was.
When a rift in the space-time continuum opened, they go on a sex adventure of a lifetime – first time anal sex, oral sex, sex with aliens, MMF threesomes, MMFF foursomes, double penetration and triple penetration.
They also encounter cavemen, early pioneer settlers, benign aliens, hostile aliens, bootleggers, the KKK and disco dancing. The only good thing, in Bob’s mind, at least, was that despite the dangerous situations they found themselves in, Zara’s appetite for sex never diminished.
When he and Zara finally returned to their own time, Bob figured nothing else could go wrong. That’s when he learned, however, that Zara was not what she seemed to be. The truth was that she was an alien who required a lot of sex to build a weapon, and that weapon just happened to be Bob himself.