Yes. Women can be in relationships with men but when it is about sex women are bisexual. So when it is only about sex women can be bisexual. When it is about relationships women are heterosexual. So at the end women are bisexual but they hide it :) I think most women have this tendency under the right circumstances but it does not mean that all women will do it in reality.
Yes, women are inherently bisexual – it is their nature. Women have a very tender side, which is apparent in their role as caregiver and nurturer. The maternal instinct soothes and calms a child with gentleness and tenderness. Through no fault of their own, men do not possess this same tenderness. A need to experience this tenderness again as an adult is what brings women together into a relationship.
It seems fairly clear that the tendency for women to be bisexual is higher, or at least appears higher. The reason for that could be any number of things. I don't think all women are inherently bisexual, but I think that over time women have become so adept at being physically attractive that other women quite readily recognize it, and may become attracted to them more easily.
While we continue to live in this increasingly sexualized society, some women may feel more comfortable exhibiting bisexual tendencies or urges. Because of the current state of the media and the culture we live in, it is becoming more and more acceptable for humans to blur the lines of sexuality and attempt to destabilize traditional ideas of identity and sexuality.
Women can not possible be inherently bisexual because there is no evidence that all women find other women attractive. As a a matter of fact, the idea of engaging in such an act might be strongly detested by some women. Also, there is no evidence that suggests this. Genetically and in terms of human nature, we are attracted to the opposite sex for reproductive purposes.
All women are not inherently bisexual, just as all men aren't. If anything, it is more socially acceptable for women to experiment with other women without being judged or harassed or labeled as gay. It is seen as harmless fun and even sexually pleasing to some men to see two women together. This doesn't make women inherently bisexual, it just means that they have less constrictions on their sexuality and are allowed to be more fluid in their decisions. Doing anything with someone of the same sex does not necessarily make someone bisexual or gay at all, it could just be for simple, harmless fun.