AIO about girlfriends dream

So during the beginning of our talking stage and relationship my [20 M] gf [20 F] told me that she had one relationship that lasted about 5 months with a guy in the beginning of her college semester. She told me it was a toxic relationship but it was her first. Eventually after 5 months, her ex ended up leaving her for another girl and this broke her mentally to where she started falling apart in classes. A year later she meets me and we have been talking for a total of 7-8 months and dating for almost 4 months now. However, 3 months into our relationship, I found out that in the first weeks of our relationship, she still dreamed about her ex (no idea if they were good or bad dreams) and was still actively stalking him on some website that allowed you to anonymously stalk people on social media. I was very upset when I found out about this but she told me that she hasn’t done it recently or in a long time and said she loved me and doesn’t miss him at all. She even offered to do a lie detector test which I know those aren’t trust worthy but still. I also didn’t find any evidence recently to tell me that she was still stalking him. So I give her the benefit of the doubt and we continue like normal. 2-3 weeks later, she tells me she had a dream and this is what she said:

“So you were rushing me out these doors but then you stopped and was like “yooo your ex is there, wanna makeout?” and lmao we started making out and I found it amusing 🤭 o and he came up to us and said something but you said smth to him but I lowk forgot what you said”

She doesn’t remember anything else besides saying she believes something scary happened at the end to the point she jolted awake. Apart of me isn’t too upset bc I know some people say you can’t control your dreams and also it was me in it too, but the other part of me is like wondering why the ex is even in the dream. I didn’t get upset with her when she told me and I just continued like normal but there’s just something slightly eating me inside. AIO about her most recent dream about her ex?

TLDR: gf dreamed about me and her making out infront of her ex and found it amusing but I’m wondering why the ex is in the dream in the first place