how did you find out s/he was cheating?

[Semperfikindoflove]

I completely agree that you can regain trust and that paranoia or extreme jealousy is something you can work on and overcome.
But only if the partner with the paranoia or jealousy issues actually realizes that it's them that's having issues and not their SO being unfaithful.
You can also regain trust after one of you has cheated. It doesn't necessarily mean that the relationship is over (well, it depends on the people invovled. If you can't forgive cheating, that's fine).
Generally what I wrote is obviously, how I see it. I don't believe in re-gaining trust for me. My trust is so hard to lose, that once someone does manage to lose it, regaining it isnt an option. If it works for others, more power to them

I've been on the receiving end of this. At some point my ex became convinced that I was cheating on him. We were long distance at the time (but had been CD for a year) and apparently because I didn't send him a text every hour or talk on the phone for hours every day, that was a sure sign I was being unfaithful.
Well... I tried to explain that it wasn't the case, but he wouldn't believe me.
His accusations were completely unjustified and I was very hurt by them. It made me realise that there's no future for us. I don't want to be in a relationship with someone who thinks that low of me. Maybe if he had realized that it was only his insecurity and apologised to me, I would have stayed with him. But unfortunately (or fortunately, for things turned out pretty well for both of us) he didn't, so there was no future for us.

I know how that is, my ex chose to do that to me when he was gone. I haven't been unfaithful a day in my life and he chose to accuse me of lying and cheating while he was gone at boot camp. I understand it's the mentality but I gave him no reason to think that whatsoever. The worst part was that he thought it was with my best friend who I had dated at one point but he and I hadn't ever done anything physically or emotionally unfaithful. It was hard and it was something we couldn't overcome because he refused to believe that things are repairable after that. But he was jealous and paranoid all of the time because of other guys examples and experiences with the military. I don't believe that all cheaters are repeat offenders by any means. I've known some very wonderful guys who had an error in judgement and hurt someone they loved, they learned their lesson and never did it again. I think it depends on the personality. I've forgiven two people for cheating on me and it always worked out fine. We just weren't compatible personality wise or relationship wise.