Between Sid & Ishani, though the feelings were mutual but not in sync, Sid's are more with the easy flow, but with Ishani a cease inbetween after life altering circumstances with Sid being her knight in shinning armour( because of her toxic past, she was anxious of its posinious possibilities streaming in her present) as certain introspections could cause confronting with dormant emotions and feelings that might lead to havoc if released - the butterfly from promo symbolic of metamorphosis, a freedom, giving wings to dream on, unshackling, throwing caution exposing her vulnerabilities & ready to explore this new experience.
Their intensity of response since the intial phase was always unguarded, instinctive & instantly instigated
the elevated nervous tension, a heightened sense of awareness, desire & denial duelling for supremacy 