Male + female = babies. I have had only male bettas but they are extremely agressive with other males, and possibly females. I never dared to mix them because 1) I don’t want dead fish 2) I don’t want fish babies. I would say separate them because you’ve had your male betta for, what, 3–4 months already? He is USED to that space and if provoked, even by a female, he could attack. Why did you buy them anyways? Betta males are meant to be alone.