Coworker dating client/tenant

my site is a mall and I brought on one of my friends as an overnighter while I work day shift. recently, we had a personal falling out. my coworker has started a relationship with an employee working at a little girls retail shop in the mall. it's against our contract, and I'm not sure if I should bring up the relationship with my supervisors. I'm worried about my coworker saying it's malicious or that I made them lose their job. the whole thing is extremely complicated. I've already reported this person for a hostile work environment, due to aggression and the lack of communication coming from them after our falling out. what do I do?