My sister suspects that my wife is cheating on me, and she has warned me to be on the lookout multiple times, but sis lives in Canada, so she cannot be sure.
Her sister also suspects that something is fishy, but again she is not sure.
I have told one of my close friends, he sort of found out by accident, he happened to visit us unannounced once and my wife was leaving just then all dolled up to go on a date by uber. So he asked me upfront, and I told him, he was quite stoked, but did not say anything to anyone.