I'm mad at my sister after she asked me when I was getting married
Why don't you want to get married?
I feel like it is a pointless ritual.
Asking when someone is getting married is normal for dating adults. You should not be mad at your sister for asking  innocent questions.
She's just teasing me knowing no man will ever marry me.
I think you are overthinking this. I doubt that is what your sister intend. That is you own insecurity hat you need to deal with.