Impossible to tell if the rat is too big without the snake in the same pic. Generally if it is the same width as the snake, you are fine. Ball pythons really get put off when their food sniffs back! As long as he shows interest I would leave the rat in but do not leave them unsupervised! A lve rat can seriously harm or kill your snake!

How big is your male and are you 100% certain about sex? This time of a year a lot of males aren't eating.