If you were in a serious relationship and you learned that your partner cheated on you one drunken night, could you forgive him/her?

I have in the past, but I won't forgive again. I'm not that stew - pid anymore. I know she will just do it again if I enable her.
I never cheated. It's despicable. I never will and I deserve the same in return. Yeah, I'm old and out of touch. So be it.