Does my ex have control over my heart still after years?

There’s a guy who seems respectful and genuine and the type of person whose qualities I’m looking for in a future husband. He wants to go on a date but something holds me back every time no matter who it is. I always think of my ex who I broke up with 2 years ago but do not want him back and do not “like” him. So I don’t know why I think of him. He was my first relationship. I want to go out with this new guy and get to know him more but when the time comes I feel as if I’m betraying my ex. What’s wrong with my?! Why am I thinking this way? It’s super frustrating!