I don't think Ayaan will give up on Kanya so easily. The poor guy's got the shock of his life and is feeling betrayed at the moment. He' s human after all. Give him sometime, and he'll come after Kanya and apologise. So, don't dismiss him as "mama's boy."
You see, if he comes back to Kanya and persuades her to get back together with him, only then can Ranbir step in and marry Kanya as the only way to stop Ayaan from marrying her.
My two bit.