What does it mean...

What does it mean when a girl (looks like a fake account) on insta adds you and tells you she has a lot to say about my boyfriend, soon as I confront him who she is he tells me the whole story from his side before she even messages me back but he deleted their "conversation" some time ago and kept it hidden from me so there was no evidence to prove his innocence? But he mentioned she sent him a photo of her "bits" randomly and him and his work colleagues were messing around? But he never bothered to mention until she messages me? Why remove the conversation if there was nothing to hide..