I'm not sure if I really buy the whole "all women are bi" narrative, given how I've seen women treat other women.
I don't remember where I heard the quote, but there's a saying to the effect of "Men and women are alike in that neither trust women." Women tend to flock together, be it at the mall, school, or the bathroom, in order to not be isolated or talked about by their peers. It's a principle of "hold you friends close, and your enemies closer." If you buy into evolutionary psychology, it may be a defense mechanism to keep from being isolated from the group, and thus be vulnerable to outside threats. There is no "sisterhood" per se among peers: only enlightened self-interest.
As you've mentioned, the feminine form is naturally eye-catching. Some women feel aroused by looking at their own bodies. But that's a whole different ballgame than wanting to be in a committed relationship. Another joke about Lesbians is that they tend to bring with them a U-Haul just to carry the emotional baggage they tend to lug around with them.
Yet, June seems to have a difficult time developing friendships with anyone, much less be in a committed sexual relationship.