This article by Robyn Ochs outlines biphobia pretty well. http://www.robynochs.com/writing/essays/…
I am sad to say that this statement by you, Dan Savage, has hurt my feelings and I feel a little betrayed. I wanted you to be an ally and the voice of freedom from oppression. What if your son DJ identifies as bisexual? Will you deny and belittle him? Tell him it's "a phase" (hmm those words sounds a little familiar) I don't mean to hit you where it hurts or use your son but it concerns me that you can toss bisexual freedom from oppression to the wind when you are such a wonderful and powerful influence on the queer community. You are belittling yourself by taking on such a small scope.
Part of being bi is the fact that you might fall for a person of the opposite gender. Statistically there is actually a pretty high chance you might, after all the majority of the population dates people of the opposite sex.
So by falling into these relationships bisexuals aren't hiding or betraying you. On the contrary they are expressing their freedom to share their life with the person they most love. Isn't this what we all want?