Not necessarily. I'm not a fan of this particular ship, but as we saw with Nina, Angel actually can be with a girl who he is genuinely affectionate for, just as long as it's that "99.99999 infinitum percent" thing that Wes talked about. Apparently, it's only Buffy who rings that particular bell for him.Angel's curse would need to be lifted.
Would Buffy and Faith accept having the same boyfriend?A couple? Sure, a couple of badass fighters.
But basically Nope. It's one of the best bromances in the 'verse but there was never any romantic chemistry there.