Guys - what is this whole lesbian fixation thing about?

While women have penis envy men have vagina envy. Now just because women are penis envy, and they are, doesn't mean they want to have a 3 some with two men. Men on the other hand are visual creatures. Men having a 3 some with two women is the closet thing they will ever come to knowing what it's like to be a woman. Some people here will disagree with me, however, many gender therapists agree.

I'm not a guy, but I noticed nobody answered your question yet, so let me..

I don't think guys are fixated on lesbians. They are fixated on 2 (or more) women (presumably straight) doing sexual acts for their (men's) benefit.

I think that's because women are in general, sensual creatures. and the prospect of looking at women doing it or doing it with 2 women or more is exciting for most men.

all women are lesbians,,just most are in denial

There's always something alluring about what you can't have.