I would, if this was troubling me and I had to be near this person for work/other reasons, find a time to take the person aside and let them know that You have boundaries that need to be respected but that they are not intended to hurt anyone, give specific examples --assure the person that this is not about them personally. People often do not know why someone seems to pull away & they may respond by 'trying harder'...
don't know if this makes sense in your situation.