Why is it women say once a cheat always a cheat?

I'm a woman and cheated once before. I've seen A lot of women on here saying basically " once a cheat always a cheat" to women about there partners that have made mistakes! Me personally that has cheated once before would never ever cheat again. The hurt and pain that I seen my ex go threw when I told him made me actually realise how much he cared for me. Which I never believed and reaslised before I cheated. So for me even though I cheated once I would never cheat again. So why do you women have these opinions on men or even women for that matter