Dealing with my extroverted friend and her introverted boyfriend problems. Advice? :/

My extroverted friend called me this morning in hysterics because her introverted boyfriend did not tell her that he had a day off work. She complained that he was "lying" to her and not trusting that she would understand his need for some time to himself. She said he was making her out to sound needy.This seemed to have really hurt her, especially considering that she had told him she needed a ride that day to a job interview and he had kept quiet about being free that day.

I totally understand how she could be hurt by this, but I don't understand the level to which she is reacting, and why it is hurting her so much, but maybe that's because I am not an extrovert. As an introvert myself, I understand where her boyfriend is coming from. I myself have told my extroverted friends many a white lie in tense moments when trying to get out of a situation I didn't want to be in. I usually regretted it, but always thought it was better and less awkward than just saying "hey, I need to be by myself now" because I didn't want to hurt their feelings or make it seem like I didn't want to be around them. That's not the case at all, but it's hard to explain that especially when they only have a small understanding if any of just how important personal space and time is to an introvert.

Anyways, my friend, who I love dearly, can come across as needy once in a while, as we all can. I personally am not sure I would trust her, or anyone, to be really understanding if they were in a position where they actually were feeling in need. Like today when she needed a ride to her interview.

How should I deal with her? She like me has emotional imbalance issues, how do I tell her that she may not think she is coming across as needy but maybe she is. How do I get her to understand where her boyfriend is coming from? Is it even possible? Maybe I should get her a book on introverts or something. I don't know. I feel helpless, and worried about them both.