How did you find that your partner was cheating?

Sometimes you don't find out until way later or someone else tells you. Sometimes there's no smoking gun but you know something is off and it turns out to be true. The sad reality is sometimes relationships end with betrayal and there's nothing you could have done differently. People cheat for many reasons - sometimes it's about them, not you. Finding out hurts but knowing is better than living in doubt. If you suspect cheating, address it directly. Either they come clean and you deal with it, or you leave. No point in limbo.