What does it mean when a guy says shes driving him crazy?

It probably means that he likes her a lot, but she does not act the way he expects or would like. One technique that some girls use that generally drives lovers crazy is what I call "hot' and "cold". Sometimes the girl acts like she really wants to be with you ; other times she seems not to care for you at all. Some girls are difficult- they are easily hurt, take things you say the wrong way, get angry but won't say why or make demands that are difficult or expensive to supply but do not appreciate the difficulty or expense if you do what they ask.