I'm at the stage where I know the theory, and could probably apply it to good effect, however it's as you say not catching feelings which is the problem.
the sex is like being on coke or some ****, honestly you can't explain it to someone who hasn't been with a BPD, the feeling they generate due to the massive amounts of oxytocin they pump out is literally intoxicating, you can't replicate it with a non.
I kind of look at BPD'S as the ultimate test of "alpha" skills, if you apply seamless game to them you can keep them around for great sex but literally one wrong move and they start the devaluation. It's especially hard because after an orgasm she starts crying and looking into my eyes and begging me to love her, but if you say you do she's gone girl on your ass!
I think I'm going to take a bit more time away from this one as recovering from a run in with her takes at least a few weeks, thankfully the recovery time is getting shorter each time. She's pretty predictable, like a robot.