Everyone deals with unwanted flirtation here and there. Some guy cat calls you in the street, and you yell something (probably mildly profane) back at him. Obviously not pleasant, but also not the end of the world. But when it happens in a work environment, it’s a totally different story. You’re probably seeing this person every day, and you don’t want to risk creating an even more uncomfortable environment for yourself. There’s no doubt that it’s a delicate situation.