My current wife knows that I'm bi and I've been fortunate to have been with women who have understood that I'm bi and, importantly, they accepted my bisexuality. Now, to your question of whether or not women understand bi guys? They're not supposed to and the "social standards for females" have decreed that they do not, cannot, and will not understand any man who would have sex with a man - and then have the nerve to want to be with them, too. Do they understand intelligently? Yes because, "Baby, I like women and men!" isn't that hard to understand but, again, social norms mandate that they do not understand bi men... while fully understanding bi women (and some blame men for the bisexuality they're enjoying). My current wife is bisexual but if you were to ask her, she'd tell you that she isn't and... I don't much care about this because I know the truth of her and we're doing quite well.
My wife will most likely never be bi. She has never given any indication of wanting to and when we've discussed it she has stated it's not for her. She does understand about me being bi and had no problem with it. In fact she encourages it. She sometimes has me tell her about how good it felt. I don't know about other women but my wife certainly understands me being bi.