I don't want to say anything against homosexuality - to be honest I think it's good that BW did that - but Vaylin?!
I mean, ***?! She's a psychopathic beast, even worse than my sith marauder, and it even seems that Arcann is scared of her. Be honest guys, would you want that? Well, she's attraktive, but imagine a romance with her. Would she kill you if you're late for a date, or would she just break all your bones, so that you will never be able again? Remember what Senya has told you 'bout her aggression (the Story when Vaylin was a little girl...)
In addition, is anyone thinking, that flirting her'd be realistic? She's your enemy, she Bad risked to cause a giantic Explosion to catch you on her own planet... I mean, *** again.
And, you think that would even fit into the lore of SWTOR? No, it wouldn't ...
The only amusing point 'bout this are the dialogues I imagine you migjt have ist Valkorion, Senya or maybe Koth, then. That'd be really hilarious.
But, no a Vaylin-Romance would be totally killing the story.