I think Vidyut is just faking it. He knows that Neil would rather keep avni in jail than leaving her with Vidyut. He trapped avneil badly. Vidyut can't love anyone else but his Mamouni! But I still hope for the triangle. Would love to see Karam as obsessed or passionate lover! And it would add much needed spice to avneil story!
He may or may not fake it, but I am sure even if not now, he might develop a strong pull towards Avni in the future to come.
About his love for Mamoni, well he has ulterior motives there as well, if not, then he wouldn't have hidden the truth of Mishti from her by saying that she died by drowning in the sea.