Someone in a relationship is flirting with me

If your seeing partner actually had their partner? will you tell them about how seeing partner treat you to the actual partner?

Not marriage/just a relationship

What would you guys do when u realise ur seeing partner who is giving you the signal has a bf/gf? Would you guys just don’t give a **** or tell her/his real bf/gf that how they tried cheating or fooling on them?

Might have been easier to write "someone in a relationship is flirting with me".

I knew this fact few days ago and I know that it’s right to stay away from that person so I am trying and doing that, indeed. But it’s the dilemma should I tell this to that person’s partner actually that person was flirting with me or just keep it as a secret and run away from him?
I saw the previous comments and referring to it as an advice. I just wanna hear more common opinions.

I knew this fact few days ago and I know that it’s right to stay away from that person so I am trying and doing that, indeed. But it’s the dilemma should I tell this to that person’s partner actually that person was flirting with me or just keep it as a secret and run away from him?
I saw the previous comments and referring to it as an advice. I just wanna hear more common opinions.

Obviously let the person partner know before they know themselves… clearly they are taking the mick and cheat like behaviour.

I think I'd want more information before claiming such as definitive conclusion, like any information at all beyond the word 'flirting'.

What information would you want

Something they said or did and whether they acted this way only to the OP or whether it's how they treat others.

'Flirting' is just too vague and subjective on it's own and could pretty much mean nothing or a misinterpretation.