I would say, nothing... Except for understanding. Men and Women both have mood swings at different times for different reasons. Women have that "time of the month" which we men have learnt to largely ignore and not get too upset with the inevitable mood swings. We men have mood swings for different reasons too, sometimes a bad day in work can cause a few days of moodiness sometimes, other causes can vary.
why shouldn't it not be about love? the world is about love.. it was love that made us (humans).. lust for some and that boils down to love for self-gratification... the world is built on love... we have hate because we loved too much and our love wasn't reciprocated the way we have hoped it would be... loads of people love money so we have corrupt officials ... like all other intangible things, love can be positive or negative...