I don’t like her romantically and want nothing sexual with her either. She acts desperate to talk to me, won’t get into more details.
I could act busy each time she approaches me, and avoid her as much as I can but I don’t know if I should tell my manager about this. I don’t even know what I’d tell a manager: “I’m informing that I want nothing to do with X and I’m going to keep my conversations with her to a minimum”?
Another idea: be boring as f*ck.
Do I tell her friends I don’t like her?
Ideally I could tell her directly I’m not interested / I don’t befriend coworkers (not true but it would work to soften the blow), but I simply don’t know how defensive she’s gonna get, laugh it off or accuse me of playing games.
Legit ask her if she’s trying to flirt with you. Act incredulous at the concept, to give her an out and let her save face. If yes, you can politely say you’re flattered but you have a personal policy to never get involved with anyone you work with. If she says no, apologize profusely for the assumption and explain the same policy, hence you’re asking.
If you think she might be the type to chase you anyway, flat out tell her the flirtation is, quote, inappropriate and unprofessional. That should deter any issues and if not it’s an HR issue.