Personal space relates to an individual’s representation of the self and the self in relation to others. Being aware of one’s personal space relies heavily on an ability to regulate behaviours and emotions. Individuals tend to seek an optimal distance during interactions, and when this space has been compromised, discomfort or dissatisfaction occurs.
You tell your friend they are sitting too close to you.
If you feel someone is too close, you should ask nicely for them to move back. Similarly, if someone tells you that you are too close, you should take a step back and apologise.