If you're talking about Blue, she's a friend who's helping out a friend. Besides the bust stuff, she's been pretty straightforward I think. Seems like Brown is the one that might not understand her preferences. If Brown is actually dating men (and hasn't said she's Bi), it makes complete sense why Blue never thinks she's an option and makes Brown's being OK with the bust stuff seem more confusing for Brown, not Blue.
Edit: "(and hasn't said she's Bi)" is added for clarity since it's apparently needed for some.