Once a cheat always a cheat? What's everyone's opinion

I think it's a case by case basis. I cannot say it depends on the cheater alone. The partner who keeps on forgiving can also be a factor for the cheater to continuously have an affair. However, I believe that a person can cheat once (for whatever reason that maybe) and can be forgiven. But, if he/she cheats twice, three times or more than, oh dear, his/her partner should not in any way, forgive. Trust is one of the main pillars of a relationship and a cheater certainly does not have that.