Ok so here are the ones I remember and yes I'm aware some of thgem might not be counted as couples:
Buffy and Riley
Zander and Anya
Zander and Willow affair
Cordelia and Zander
Giles and Ms. Calender (Jenny)
Angel and Darla
Angel spike dru triangle
Buffy and Ben (the guy that turned into Glory)
Buffy and Robin Wood (he was in final series, principle I think. Well they dated but not sure if you would class them as a couple)
Faith and Zander hooked up for one night
Wesley and Cordilea kissed
Giles and Joyce hooked up while they were under the chocolate spell that made them act like teenagers.
Buffy and Scott (he was the guy she dated after she sent angel to hell but before he came back)
Buffy and Parker Abrams (she hooked up with him at the start of series 4)
Sorry can't check out your fb page as I'm not on fb :(