YTA.

Normal for couples to see each other more frequently before they move in? That's a lame excuse and you know it.

Bianca signed onto the lease under the impression that she'd be living there with Liv, not with Liv and you. It's shitty to essentially force her into a situation she is clearly unhappy with when she didn't even agree to it in the first place. She is paying her part of the rent and she deserves to feel comfortable in her own space, something which she is not allowed to do since you have basically unofficially moved in.

It wont kill you to not stay over with your gf as much for a few months until you guys get your own place. Or, if that's really so difficult then have your gf come over to your place. Even if its small it's still a better option than continuing to be so inconsiderate.