Hello! I have a predicament…

Hello! I have a predicament... (let's call them A!) So recently there's this person I really like and have feelings for, but they are in a relationship. The thing is, A also likes me a lot as well, but they are hesitant on telling their partner (let's call them B!) that we like each other and have already done stuff with each other. Should I personally tell B? Do I tell A to tell B about us? I'm afraid to tell B, but at the same time, I feel very bad for B since they are being hurt even more as time goes on. Life is hard and complicated
Hello! I have a predicament… (let’s call them A!) So recently there’s this person I really like and have feelings for, but they are in a relationship. The thing is, A also likes me a lot as well, but they are hesitant on telling their partner (let’s call them B!) that we like each other and have already done stuff with each other. Should I personally tell B? Do I tell A to tell B about us? I’m afraid to tell B, but at the same time, I feel very bad for B since they are being hurt even more as time goes on. Life is hard and complicated

You should tell B because no one deserves to be treated the way you and A are treating them. Person A clearly needs to work on their maturity and their values before being in a committed relationship with anyone again. Do you really want to be in a relationship with someone willing to cheat on and lie to their current partner?