What's with the Hollywood Bisexual Trend?

There is a big difference between being sexuality interested in the same sex, and being romantically interested. It's likely that these girls are okay with sexual encounters with girls, but not interested enough for long term relationships. In our society, this is far more acceptable for women than for men, and this is the phenomenon you are observing. It's also a lot less taboo, and you also have to consider the "two-girls" factor. Sometimes when a celebrity's popularity (mainly female celebs) is slumping it isn't uncommon for some of the more scandalous types to have a fling with a girl to increase her male viewership, not unlike Megan Fox or Lady Gaga to do. It's a publicity stunt, and men tend to find two women together arousing, especially attractive women. It's a social political thing, that revolves around sexism, and it's a load of horse manure. At least that is my opinion on it. Hope this explains it.