Imagine that you read about a new model of the fusion processes in the cores of massive stars. The new model correctly predicts the luminosity of a star given its mass and core temperature and pressure. What additional observation(s) must the model correctly predict if it is to be taken...
If she had sex with a dude after 6 months and ended up breaking up with him, then maybe she just wants this time to be a sure thing. Girls generally think of dudes as more physical than emotional so she might be testing you. (Girls are bitches like that. =D)
If you're serious about her, then...