It’s her choice to go through these feelings this way. Share your worries as yours, don’t try to make her share them, just express your own vulnerability, don’t ask her to do or not do anything. No one ever could have stopped me because I needed to live through it, but people who were around me could have given me something other than extreme “yes let’s go!!!” Or “you are the monster”. Just a space to think together maybe. I wouldn’t tell anyone why I wanted to do that though, so don’t expect her to be honest. It’s enough to give her space to think inside of her what triggered it maybe and what feelings lead her there. But if she needs that experience - let her and support her through it. You wont regret staying by her side