and she also knows in her heart the amount of interest manik is showing nandu he hd never shown to her. Well I rem d scene when after dat accidental kiss when alia is clearly showing her discomfrt manik didnt bother to pacify her dat much he was thinking about nandu and even when alia said to decide btw her & nandini he didnt say anything he realsed her when it was a choice btw fab 5 & nandu. And even alia knows dat she as a individual dont hv any power over manik.
She has doubted Manik from the beginning, from the time he became obsessed with Nandu and he always wanted her around for whatever reasons. She also knew that once Manik knows about the goon-sending he will leave her. She never trusted him. That means she must have known at some sub-conscious level that Manik was not into her as she was into him. And this started surfacing when Nandu came into picture and Manik started spending more time thinking about Nandu than being with her. She had seen them exchanging looks in the store room and then in the jungle he saved Nandu.