I love my sister but why on earth would you go on a girl-cation over a holiday rather than spending…

I love my sister but why on earth would you go on a girl-cation over a holiday rather than spending it away from your baby. I feel like she's feelon a little lost these days. She finally left my brother who has made so many mistakes so I am hoping she's not projecting that hurt on their son. What can I do to help her? (I'm not the type to get judgey but I am a little worried)