She was just laughing and clapping at AR's Journey of Love (supposedly), but in reality, laughing at Sidma's misery.
She is the one who is responsible for SR's current situation.
Reasons:
1. She was the one who forced Sid to hide the YuNa truth from his mom for her benefit, despite knowing the rough marital patch that Sid was going through.
2. Though she accepts AR's love, yet she is unable to accept Sid's feelings towards Ridz.
3. Despite being Sid's "Friend", she sees love only in Armaan's eyes but not in Sid's. 😡
4. In today's epi, she has crossed all limits. She and Raj were practically cheering and whistling at AR's Love, completely oblivious to her Friend's (Sid's) misery at the same. She displayed no emotions towards Sid's condition. Raj can be forgiven because he never claimed to be Sid's friend. But Naina's actions were unforgiveable.
5. True, AR's love story was admirable. She can admire that, no problem. But she showed no emotions towards Sid. Had it not been for YuNa, Sid's mom would have known the truth and SR would have been together without any misunderstandings.
6. She was also insensitive towards Ridz humiliation at her past being exposed in front of everyone.
Her actions showed that she is an insensitive and extremely selfish girl, who does not deserve to be Sid's friend. 😡