HI, so I have been typing to find this fic for a few days now. Im not sure if I'm mixing up stories here so sorry if I am.
Spike gets a new job in America, where he meets Buffy who takes him to a sex club. He later finds out she's the bosses(Giles) daughter.
Later Giles let's spike stay with them, where spike overhears Riley and Buffy talking. Somewhere in the story Buffy gets drugged in the sex club and spike gets stabbed.
I think faith is a dominatrix.

Hi,
I haven't read it yet but it made me think of the summary of Blonde Across the Pond by -Carrie-Ann-.

Summary: Based on a challenge by Killjoy and told mainly from Spike's perspective. After a fun weekend where he partied, seriously drank, danced and had the best shag of his life William "Spike" Pratt goes into work to meet his new boss......one Rupert Giles.
But Spike gets the shock of his life when he realizes the best shag of his life he got the last weekend is his new boss's oldest stepdaughter! Oh this isn't going to end well for him.... especially when she keeps flirting and secretly touching him while her dad is around.

After getting a glimpse, I think it might be it.

Yess! Thank you, this is it