Would I play a role in his cheating?

So there is this guy… he has a girlfriend. She says she is his girlfriend. His family met her, he introduced her to his family as his girlfriend. He does the same with his friends and other people. But he tells me the girl is not his girlfriend. He says he has a girlfriend but won’t say who it is and says the girl who is obviously his girlfriend is not.

Would I play a role in his cheating?
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