Confusing as it sounds (not how it is written, but the illness itself), Perna has got it right. As a BPD myself, I can tell you that there is nothing that you can do to alter how she will feel from one moment to the next. We can't even predict that! The best we can do is try to be aware of these emotional upheavels as they come upon us, and do our best not to let them overwhelm us too much. Damage control is what I like to call it.
You are a brave, brave man to take on a BPD. I admire your willingness to understand, too. Most don't even attempt this, and if they do, will eventually give up because it is such a difficult illness to deal with. I am constantly amazed at my boyfriend for his "intestinal fortitude!"
Anyway, as Perna pointed out, you MUST do what is good and right for YOU, first and foremost. A borderline can easily sap you of all your energy. We are also very good at manipulating people and/or situations. This is as a result of our overwhelming desire to feel safe and secure, not for malicious reasons as one would automatically assume.
However, the fact is, we should not be able to control you like that. You must maintain your boundaries because ours keeps shifting. This way, she will always know where YOU stand, even if she doesn't know where she does.
I have gradually found constancy in my moods and my own boundaries through my boyfriend's ability to maintain his own. Otherwise, I would have dragged him off into the wild and tore him to shreds, just like the rest of the poor souls that came before him.
As a borderline, she will always be self-analyzing which may bring her to the point of paralysis (ie not calling), because she is unsure of pretty much everything. Talking is good. Talking is very, very good.
By the way, I don't think women have changed that much since you have been isolating, unless of course, your isolation started some 40 years ago. And even if it did, we still like to be indulged in the same ways.
All the best to you!
Altered State