Not everyone feels it's appropriate to share every detail of their past with their significant other.
If the other person is a guy, though, I think once you become intimate
and start sharing what turns you on, the interest in other women would
come up if you're bi.
I suppose intimacy comes in many forms but intimacy, by definition, is
sharing your innermost private thoughts, emotions and actions with
I know women who have chosen not to share their bisexuality with their
male significant other and although they manage and probably have great
relationships, their intimacy is not as deep because they choose to
leave that out of the things they share with their partner.
As far as being "out" to everyone like friends, family and neighbors, at
work, etc., unlike lesbians, who, in order to function normally in
society and have relationships, must at some point, tell their loved
ones what's up, the bisexual woman can keep it to herself and close
friends or whatever, until or unless she chooses to have a long term
relationship with another woman. There is no fighting for equal rights,
etc., for the bisexual woman in a relationship with a man.
I think it's probably easier in life to deal with everyone if you do
eventually "come out" to your family, but if the situation doesn't ever
present itself where it is necessary, there's no impetus to do so.