My first relationship had me dealing with quite a few cheating situations.

I tried and tried to make it work, but eventually stood up for myself and walked away.

I have zero tolerance for cheating since then. My take on it is when I enter a relationship, I make sure it's to be exclusive. The partner breaks that promise... it's a lie. And in my experience... liars will continue to lie if you nuture the habit by caving to them.

Hell, my first ex-girlfriend still lies to me nearly 25 years later even as a friend.