Tested with my own game.
When the scene with Bree and Sasha took place, the girls were both at 55 for kinkyness and lesbian interest (I don't think the lesbian part is important, but better safe than sorry
).
They argued, but in the end they both stayed home. So I'm pretty sure 55 is a good number if you want to keep Bree with you.
During the following days, they never argued anymore.
To raise faster the kinkyness, watch SM Porn at the TV and give as a gift the book "A Sex Slave Story" (you can buy it repeatedly at the bookstore).
NOTE: donating the Sex Slave book decreses love of 1 point (for Bree, at least), but it's not that important. There are DOZENS of different ways to increase love: by talking, by eating together, by improving your charm, etc.