at this point, given her aversion to them being on camera together, they might as well be fucking -- sister brother or otherwise. her facade is the thinnest it's been.I think Chantal was terrified Bibi would come home with his new girlfriend and we’d see them all up on each other on camera. The way a couple acts compared to brother and sister is obvious. She doesn’t want the happy couple ruining her YT facade, it also explains why she got her trigger finger ready to go the minute they walk in.
The sister/GF has always been told Chantal is a roommate and that’s true. It’s obvious she hasn’t had a romantic relationship with Bibi in a long time. The GF isn’t worried because she took one look at Chantal and decided the 400 lb beach ball is no threat to her. She probably thinks Bibi is so sweet for tolerating the crazy fat girl and helping her out.