The bisexuals who "picked a side" are invisible to everyone but themselves and their most intimate friends. They go unnoticed. It's only the ones who are fitting a negative stereotype of invading lesbian's spaces and trying to get threesomes with their boyfriends, that are given attention.
As sunflower said, people do not see inside your mind, they see your outward behavior.
I guess that is one of the main points. Bisexuals also face prejudices (like this "not beeing able to decide an just trying out", etc.) which is partly rooted in beeing invisible as soon as they have a partner. But Bisexuals do not face the same kind of discrimination as lesbians do. Beeing invisible also means having the privilige to be able to hide ones own sexuality. It's impossible to "see" if the two of a heterosexual couple are hetero- or bisexual. While I can understand that many bisexual also want to meet and talk (and live) separated from heterosexuals the fact, that they have this privilige, also means that there is just not the same "need" for a safe space or a separated space.
Or to give a different example: I grow up having two nationalities, and after getting married (and getting an "unsuspicious name") things got easier bc people don't know about my second nationality. Even though there is stuff I wouldn't talk about with germans (living in germany btw), I do not feel comfortable in "foreigner only groups". I prefer talking to people who are also "mixed". And yes, it is definetly a (hurting) privilige beeing able to hide my second nationality.
Beeing a lesbian and beeing a bisexual are two completly different things - two completly different worlds. If you happen to fall in love with someone who lives in a "completly different world" that can mean a lot of work...doesn't alway have to be about sexuality. Age, naionality,social class - differences can always mean problems. Some only cause small problems, others may even destroy a relationship. Depending on who you are and how you deal with differences, you may or may not be able to have a relationship with someone beeing completly different.
What I wanted to talk about is not whether lesbians should try hard to get more involved with bi women.
One should never "force" oneself to be in a relationship. But aside from that, I think, women in generall need to get more involved with each other. This man-centered culture isn't just a turn off, it ruins lives. The lives of homo-,bi- and heterosexual womens. Many bi- and hetereosexual women are very unhappy with their lives and relationships. And it often has something to do with everything allways beein about men. Getting rid of this man-centered culture would also reduce some of the "problems" between lesbian and bi women. And it would also erase a lot of the prejudice that exist (for example: heteroesexuals would stop pretending to be bi just bc man find it attractive. Therefore, the prejudice would also disappear).
As women, we should try and understand and respect each other. But I don't think, that a lesbian needs to date a bi. If you don't want it, then you don't want to.
Is there a way to overcome the feeling you are not enough for your bisexual partner (in any way, not restricted to sex)?
Why do you feel you're "not enough"? That sounds like your afraid of not beeing "as good as a man".