Legal definition is:
1-(1) A person (A) commits an offence if—
(a) he intentionally penetrates the vagina, anus or mouth of another person (B) with his penis,
(b) B does not consent to the penetration, and
(c) A does not reasonably believe that B consents.
So, going by the question, I see no issue with it being called rape if the other person continues to have sex. However, if it stops, then there should be no case.