Generally, in TV dramas, when the female lead cuts her finger while chopping vegetables, the male lead gently grasps her hand and then sucks on the finger to clean off the blood. The cameraman would then take a clear close-up shot of their faces, and in such a scene, their gazes would be interlocked, full of tender affection.
As it stands, although Xia Siyu and Bo Yan don't share affectionate gazes, they are indeed engaging in a rare and peaceful eye contact. As long as two attractive men and women hold hands and look into each other's eyes within the same frame, the atmosphere becomes instantly ambiguous.
The audience also feels tense.