Jenna and Blake were discussing a lot of things when Clara burst into Jenna's room. The pair of blue beads glared at Blake who didn't let go of Jenna's hand.
She was cynical not because of the intimacy of the two. To be more precise, it was just one of those petty and trivial things that wouldn't be a reason to be angry.
Another thing that she has a problem with is how negligent Blake was in caring for her, so Jenna has to go back to dealing with drugs and the hospital. Don't forget, Clara is one of the smartest students in the medical department. She knew, or even really knew, how to make her pretentious attitude look convincing.
In fact, Clara's main purpose in being cynical was to mentally intimidate Blake, then decide to withdraw from Jenna's life, once again. However, it seemed that Clara had miscalculated.
