I dunno man, Tamsin might even just be saying that she's Bos girlfriend. Not they're girlfriends.  It's not like she's said Bo belongs to her.  I mean, it's odd. She's only showing jealousy towards Lauren.  I have a feeling there's a lot more that's going to go down between Valkubus. Good and bad. Put it this way, I don't think it's all of a sudden going to stop. Bo has started to reciprocate more and more as the episodes go on. Her facial expression even showed concern/a slightly crestfallen look when Tamsin said the football player was hot in the photo when they were discussing the case with Lauren and Dyson at the beginning. Her face goes from kind of light and carefree to concern within a second.

I find it verrrry interesting that while Bo was on the phone to Lauren and said “No, I need you” she was also directly looking at Tamsin and placed emphasis on the ‘you’. Very clever filming. It can be taken in a million different ways. Bo being assertive about how she feels for Lauren, Bo basically saying to both of them that she needs them both, etc. Either way, I don’t think Bo is oblivious. I just think she’s preoccupied. She probably also finds it slightly amusing that two women are obviously fighting for her. Hey, sounds bad but there’s worse things.