So you’re 16, and you’ve had a couple of crushes on boys turn into enough of a relationship each time that you changed your status on Facebook and, OMG so did he, and the endings were temporarily tragic and more lastingly awkward, but it all seems pretty par for the course until you find yourself head-over-heels and giddily blindsided by a much deeper love…for a girl. What does that mean?
Are you a real lesbian? Or, if the “you” above is male, are you NOT a real gay guy? That was just puppy love before? Are you actually bisexual? Will you ever fall in love with a boy again? And if you do, what would THAT mean? Can you trust your own feelings? Can sexual orientation re-orient? How do you explain this to your friends? To your ex?
What does the research say? This is a relatively new area. Some work suggests changeable attractions might be more common for women than for men, but maybe only because it has been more studied to date. Lisa Diamond: “After all, if female sexuality is fluid, one might argue that we shouldn’t bother distinguishing between lesbians and bisexuals to begin with. Perhaps all lesbians are ‘potential bisexuals’ and vice versa. Yet this would make sense only if all women appeared to be equally plastic in their sexuality, and the findings of this study suggest that this is not the case. Rather, some women appear to experience (and perceive the possibility for) greater change in their attractions and behaviors than others, and these women appear most likely to adopt non-lesbian labels or to change labels over time, even if they are predominantly attracted to women.” 
Diamond’s study seems to open a dangerous avenue for anti-gay proponents. If sexuality is in fact changeable, and if at least some women feel a certain degree of choice in the matter, does that allow for moral judgment, that is, a “better” form of sexuality that one should choose or move toward?
Just because a pattern of attraction might shift over time doesn’t mean we control the shift, any more than we control the attractions. Human history across the spectrum shows our utter lack of control over the who in our attractions. Think back: haven’t you been mystified or even embarrassed by feeling that zing for someone completely unexpected? Sometimes those attractions are not appropriate to act on (one’s teacher, someone in a committed relationship, etc.), but what if the gender of the person who inspired the zing were the only part outside of your pattern of “appropriate” attractions?
Diamond told Troy Williams in an interview in 2009, “there were women who I studied who identified as bisexual but experienced their bisexuality as something that had more to do with a particular relationship they were in, rather than a stable trait. They say, ‘I thought I was heterosexual and then I fell in love with this woman. I don’t know what that means, and I don’t know what will happen in the future.’ That open-endedness is why bisexuality gets stigmatized….The majority of women who experience any same-sex attractions at all, actually tend to experience attractions for both men and women…. This is an idea that many people find very threatening. It’s much more comfortable for the culture at large to imagine that everyone fits into a gay or straight box.” 
What do your teens think about this? Is bi “trendy” in their school? So they feel the “pressure to choose?”
 Diamond, L. M. (2000). Sexual identity, attractions, and behavior among young sexual-minority women over a two-year period. Developmental Psychology, 36, 241-250
Diamond, L. M. (2008). Female bisexuality from adolescence to adulthood: Results from a 10-year longitudinal study. Developmental Psychology, 44, 5-14.