Should I Tell this girl that her boyfriend flirts with me?

This boy I work with constantly flirts with me and he tried to get my number and social media several times so that we could talk. I obviously have a boyfriend (Which I told him and he didn’t believe me) and I don’t want him anyways... I had no idea he had a girlfriend. I just found out today. The thing is, my other coworker goes to school with his girlfriend and she “accidentally” said something about him cheating on her. If it were me, I would want to know if my man was flirting with other girls and acting single. Come to find out his girlfriend is friends with my friend.
Should I Tell this girl that her boyfriend flirts with me?
Should I Tell this girl that her boyfriend flirts with me?
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