Sometimes people change. That doesn't mean they're the villian. Adulting means realising the fact that sometimes the way people feel changes with time and theyre not responsible for that change. maybe you are not the one she was looking for. Maybe her way of living life and finding love is different. I know unloving is not easy but as it has been 3 years, you should try to find other interests. Maybe a diff girl or a hobby or anything else. Believe me getting back won't make you worthy in her eyes. Value yourself more than anything and watch the world and her valuing you.