I'm not going to tell a suspicion about a girl cheating
Why won't you say anything?
I don't want to get involved
Involving yourself in other people's relationships will only harm you more than it helps anyone. You may end up exhausting yourself mentally trying to help and also making them both dislike you.
Thats really true, good thing I am not the one cheating!
Indeed. The best course of action might just be to ignore it and mind your own business.