I'm going to tell my friend that his girlfriend has been cheating on him.
Is warning your friend about you or him?
I try to protect my friends, but my friend ignored my warning about this girl.
That's a nice mindset to have towards your friends. Although the situation is a sad one, I'm sure your friend will appreciate you discovering this infidelity.
Thanks, I'll try to break it to him gently.
I think you're doing the right thing. He may not be happy to hear it but she is taking advantage of him by cheating and he deserves to know the truth.