I’ve only had two FWB experiences that stayed FWB and none of them stayed uncomplicated. So, except for the money, I’ve come to prefer this. (Though I’ve managed to fuck this up a few times, too.)
Complications aren’t always bad. In fact, the best relationship I’ve ever had started off as an FWB thing and we were off and on for five to seven years (depending on your definition of “off”). But the other times… the browbeating and the drama… ugh. No. A lot of variations on “why don’t you feel what I feel.” Even the memories of it are draining. So, other than The One, I've had two situations that lasted about a year each. The others were a few months.
For me, the sex is way better here. Despite what Hollywood and the sitcoms say, men aren’t the only ones who are clueless in bed. (But like Richard Pryor said, there’s no such thing as bad pussy, so I pressed on.)
As for how it starts, there are websites for this kind of thing. I’m a terrible pick-up artist, so most of them started online.
But having said all that, if I could find an FWB situation without the emotional blackmail, I’d be out of here like a shot