I don't think so Vanraaj is faking all the scenes with Anupamaa as he claims to Kavya. I mean during the dinner scene, no one was around, he don't need to fake. He can have the dinner too as Anupamaa permitted him to have pasta. But he was happily having dinner after everybody went inside.
Moreover, when they had been talking inside the bedroom, it looked like a genuine scene. It felt Vanraaj's emotions are real.
I guess , after faking, he got into real emotions or betraying both Anupamaa and Kavya.