When reading the body language of a jealous man or woman start with looking at the eyebrows and the forehead and then go lower from there. You will see signs of anger or sadness in the eyebrows. The face may be tight and the lips may show disgust or anger. In some cases it may look like the man or woman ate a lemon and on the other end of the spectrum you may see the man or woman show no facial expression at all.
↑ This is a scene where Kian tickles Bobby. It is as clear as day that Jc got jealous.
↑ After Kian tickled Bobby, Jc laughed it off for a few short seconds and then his expression went back to show jealousy - as it's seen in the second photo.
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A jealous man or woman may find the need to stay close to the person that they are interested in. The man or woman may stay close to the person and need close physical contact and in some instances they may need to be held or touched constantly. ↓
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The eye contact of a man or woman that is jealous will be focused on one of two parties or both. The man or woman will keep an eye on the person that is the center of attention. This will be more of a stare than eye contact to keep up with the state of being jealous.
The jealous man or woman may not pay attention to others to keep their eye contact with their "target". ↓