There's a lot of blame for Bianca on this, but why is no one blaming Varric?
He's the one hung up on her. She may have turned him down, and even many times, but he sought her out for work, and she did it (and screwed up massively, though that doesn't seem to be the issue people have with her). She obviously cares about him, but it could easily be the care of a former lover and friend. It seems like a lot of 'Evil woman who must be dangling Varric on a string!'- but... it seems to me more like someone who has moved on with her life, and someone pining after them even though they know that.
He contacted her, not the other way around. It's sad for Varric as he loved her, but I don't see how it's her fault that he's in love with her.
I agree - Varric is also at fault. Sadly, he comes across as rather pathetic now that we know more about the story. Particularly his 'relationship' with crossbow!Bianca. It was cute/funny in DA2 - but now we know more, it seems ...sad.
That said - I do still find fault with Bianca. She decided to stick with family/status and marry the guy her family chose for her. She stood Varric up at the altar (his words, but that's all we know). Yet, she chastises him for not keeping in touch - which they have been for at least 15-ish years. And invites him to see her workshop (before her husband comes home). She's keeping him in her world - blatantly ignoring the risk it is for Varric (her family sends assassins after him). Yes, Varric is a willing participant.
I just think...Bianca (the real one), must realise that Varric is still pining. And yes, we don't know the whole story. But Varric isn't going to let go - he agrees to visit her home. If you really loved someone (romantic or as a friend), you'd want them to move on. Particularly if you chose someone else. This is a 15 year old issue. 15 years since she chose someone else and continued to keep Varric around - as a friend or whatever. And Varric hasn't moved on. It is a bit sick. Bianca comes across (to me, at least) as having her cake and eating it too. Varric is a willing idiot, yes. But really - let the guy move on. Force him if you have to. Its what a friend would do, and it is what she should do, since he clearly hasn't let go.
Edit: Also - Iron Bull refers to Bianca as Varric's 'girlfriend', and Varric doesn't disagree. Which is either him being delusional, or they are actually still sleeping together even though Bianca is married. Either way - and both possibilities are a bit off-putting - I really dislike the Bianca-Varric thing. And as I like Bianca otherwise, it is a bit disappointing.