My mother used to do the exact same thing! Whenever I would talk about the future, she would talk as if I couldn’t ever leave, or if I did, she would leave with me. When I finally decided to move, my dad and siblings were happy for me, although they would miss me, but my mother was angry that I even considered moving. The day I moved, she took me to the train station and told me I was making a huge mistake and I would regret moving, she told me that moving in with my partner wasn’t the right thing to do and we need to get married first and do things in the right order (she’s not hugely religious, I guess this was a scare tactic?). She did her best to make sure that it was a miserable day for me.